OXY-ACETYLENE 

WELDING 
AND  CUTTING 

SWINGLE 


Oxy- Acetylene 
Welding  and  Cutting 

Including 

The  Operation  and  Care  of  Acetylene 
Generating  Plants 

And 

The  Oxygen  Process  for  Removal 
of  Carbon 


By 
CALVIN  F.  SWINGLE,  M.  E., 

Author  of   "The  Twentieth   Century  Handbook  for  Steam 
Engineers  and  Electricians,"  etc.,  etc. 


ILLUSTRATED 


CHICAGO 
FREDERICK  J.  DRAKE  &  CO. 

Publishers 


^ 


Copyright  1915 

By  Frederick  J.    Drake  &  Co., 
Chicago 


r 


PREFACE 


The  Oxy-acetylene  flame  is  now  used  to  advantage 
in  welding  practically  all  metals,  as  steel,  cast  iron, 
malleable  iron,  brass,  bronze,  copper,  aluminum,  sheet 
iron  and  silver.  Its  success  has  been  proved  beyond 
a  doubt.  Engine  and  machine  parts  of  any  metal, 
automobile  castings  and  the  like  are  as  strong  as  any 
part  of  like  dimensions  when  welded. 

A  brief  description  of  all  principal  kinds  of  weld- 
ing is  given,  including  fire  welding,  welding  by  water 
gas,  thermit  welding,  brazing  and  blowpipe  welding. 
The  advantages  and  disadvantages  of  each  are  dis- 
cussed. 

Manufacturers,  contractors,  machine  shops,  garages, 
blacksmiths,  boiler  makers,  repair  shops,  foundries, 
steel  mills  and  railroad  shops  are  rapidly  adding  the 
oxy-acetylene  process  to  their  equipment.  In  cutting 
beams,  girders,  steel  sheeting,  heavy  piston  rods,  steel 
plates,  gates  from  steel  castings,  wrecking  steel  build- 
ing frames  or  bridges,  the  work  can  be  done  much 
cheaper  and  in  less  time  than  by  the  old  methods. 

In  the  preparation  of  this  book  the  author  has  en- 
deavored to  cover  every  practical  point  in  the  process 
of  welding  and  cutting  and  the  removal  of  carbon 
with  oxygen.  Enough  of  the  theory  has  been  in- 
cluded to  enable  the  practical  man  to  acquire  a  thor- 
ough understanding  of  the  subject. 

Reference  to  the  table  of  contents  on  the  following 
pages  will  show  the  scope  of  the  book.  Numerous 
illustrations  of  distinct  advantage  to  the  operator  have 
been  included. 


CONTENTS 

CHAPTER  I 

PAGE 

WELDING: — Various  Methods — At  the  Forge — By  Water 
Gas — Thermit  Welding — Brazing — Blowpipe  Welding 
— Adaptability — Quality  —  Economy  —  Convenience  — 
Cost  of  Material 9 

CHAPTER  II 

WELDING  FLAMES: — Oxy-Acetylene  Flame — Temperature 
— Combustion — Utilization  of  Heat — Regulation — Oxy- 
Hydrogen  Flame  —  Temperature  —  Uses  —  Other  Gas 
Flames — Oxy-Coal  Gas — Oxy-Benz 18 

CHAPTER  III 

OXYGEN: — Properties,  Physical  and  Chemical — Manufac- 
ture— Electrolysis  of  Water — Extraction  from  Air — 
From  Chlorate  of  Potash — In  Cylinders — Compression 
— Volume — Pressures  and  Temperatures — Handling — 
— Valves — Purity — Analysis  28 

CHAPTER  IV 

ACETYLENE: — Carbide  of  Calcium — Manufacture  of  Car- 
bide— Classifications — Generators — Principles  of  Pro- 
duction— Heating — Polymerization — Excess  Production 
— Classification — Comparison  of  Systems — Water  to 
Carbide — Dipping — Carbide  to  Water — Automatic — 
Non-Automatic — Working  Guarantees — Special  Gener- 
ators    48 

CHAPTER  V 

ACETYLENE  GAS  PURIFICATION  AND  HANDLING: — Impuri- 
ties— Purification  for  Welding — Process — Materials — 
Catalysol — Purifier  Position  and  Maintenance — Instal- 
lation and  Maintenance  of  Plant — Location — Insur- 
ance Regulations — Charging  and  Cleaning — Precau- 
tions— Light — Dissolved  Acetylene — In  Acetone — Por- 
ous Materials  —  Cylinders  —  Contents  —  Use  —  Advan- 
tages— Manipulations  and  Precautions 67 

7 


CONTENTS 


CHAPTER  VI 

PAGE 

OXY-ACETYLENE  TORCHES  :  — Requirements— Classification 
— For  High  Pressure — For  Medium  Pressure — For 
Low  Pressure  and  Fixed  Delivery — Injector  Action — 
For  Low  Pressure  and  Variable  Delivery — Welding 
Torches 85 

CHAPTER  VII 

CHARACTERISTICS  OF  WELDING  TORCHES: — Choice  of  Torch 
— Medium  Pressure  —  Low  Pressure  — Weight — Man- 
agement— Maintenance  98 

CHAPTER  VIII 

WELDING  .  INSTALLATIONS  :  — Piping — Connections — Safety 
Valves — Oxygen  Reducing  Valves — Flexible  Tubes  and 
Connectors — Welding  Table — Preparation  of  Welds — 
Adjusting 109 

CHAPTER  IX 

PREHEATING  AND  ANNEALING: — Expansion  and  Contrac- 
tion— Heating  Agents — To  Restore  Iron  and  Steel — 

Goggles — Torch  Lighter — Accessories   133 

CHAPTER  X 

OPERATING  A  WELDING  INSTALLATION: — Testing  the  Plant 
— Selecting  a  Torch — Hydraulic  Valve — Starting — 
Regulating  the  Flame — Management  of  Torch — Han- 
dling Torch — Position  of  Welding  Rod — Acetylene 
Regulation— Oxygen  Regulation — Procedure — Stopping 
the  Installation — General  Advice — Handling  Work  of 
Varying  Thickness — Thick  and  Thin  Pieces — Clean- 
ing   144 

CHAPTER  XI 

METAL  WELDING  PRACTICE: — Fluxes — Welding  Rods — 
Steel  Welding— Cast  Iron  Welding— Welding  Cylin- 
ders— Malleable  Iron — Aluminum — Crankcase  Welding 
— Brass,  Copper  and  Bronze 163 

CHAPTER  XII 

OXY-ACETYLENE  CUTTING  :  — Apparatus — Portable  Appa- 
ratus— Multiple  Jet  Torch — Lighting  and  Operation — 
Operating  Cutters  178 

CHAPTER  XIII 
OXYGEN  CARBON  REMOVAL  :  — Process — Outfit — Operation  .183 

INDEX    ,  ..186 


OXY-ACETYLENE  WELDING 
AND   CUTTING 


CHAPTER  I 

WELDING 

The  fusion  or  welding  of  metals  is  accomplished  by 
an  intense  heat  concentrated  at  the  location  of  the 
weld.  The  temperature  of  the  oxy-acetylene  flame 
taken  at  the  extremity  of  the  white  jet  has  been  cal- 
culated to  be  4000°  Centigrade,  or  7232°  Fahrenheit. 

In  practice  a  temperature  of  approximately  6500° 
Fahr.  is  obtained  by  means  of  the  oxy-acetylene  pro- 
cess, and  this  temperature  is  more  than  sufficient  to 
melt  any  of  the  commercial  metals.  By  the  applica- 
tion of  this  temperature  the  metal  at  the  point  of  treat- 
ment is  rapidly  reduced  to  a  liquid  molten  state,  flow- 
ing together  and  thoroughly  mixing  with  a  proper 
quantity  of  metal  added  by  the  operator  to  fill  up  all 
the  crevices.  The  fluid  mass  thus  formed  does  not  re- 
sult in  merely  cementing  the  two  pieces  of  metal 
together ;  it  fuses  them  into  one  piece. 

VARIOUS  METHODS  OF  WELDING 

In  order  to  appreciate  the  advantages  of  oxy-acet- 
ylene welding  as  compared  with  other  methods  it  is 
well  to  consider,  briefly,  the  leading  methods  of  unit- 

9 


10  OXY-ACETYLENE  WELDING  AND  CUTTING 

ing  pieces  of  metal  'by  *  the  weld,  most  of  which  are 
still  used  to  some  extent. 

Welding  at  the  Forge. — This  method  has  been 
known  from  the  most  remote  time.  Its  application, 
however,  is  practically  limited  to  iron  and  steel.  A 
joint  is  obtained  by  energetic  hammering  together  of 
the  two  pieces  of  metal  which  have  been  previously 
brought  to  a  welding  heat  in  the  furnace  or  forge  fire. 
The  important  points  connected  with  this  method  con- 
sist in  the  ability  to  recognize  the  welding  heat  and  to 
avoid  burning  the  metal  by  going  beyond  this  point, 
and  the  difficulty  of  so  joining  the  metal  pieces  that 
the  weld  is  perfect  over  the  entire  surfaces  that  are 
to  be  joined.  Metals  can  only  be  welded  between  cer- 
tain exact  limits  of  temperature,  and  it  requires  skill 
and  experience  to  be  able  to  know  these  temperatures. 

The  success  of  a  fire  weld  depends  on  the  exact  ex- 
ternal observation  of  temperature  and  the  state  of  the 
surfaces  to  be  united,  because  all  interposition  of  slag 
or  oxide  hinders  complete  welding. 

It  is  therefore  necessary  to  sprinkle  the  surfaces  to 
be  t welded  with  a  flux  capable  of  dissolving  the  oxide 
of  iron  and  to  form  with  it  an  extremely  fluid  com- 
pound which  can  be  expelled  by  hammering.  As  for 
the  brazing  of  iron,  the  materials  used  for  fire  welding 
are  generally  white  sand  and  borax.  Certain  special 
materials,  of  satisfactory  composition  and  easy  use, 
are  sold  and  give  excellent  results. 

Fire  welding  has  the  following  disadvantages : — 

(1)  It  is  necessary  to  heat  a  large  portion  of  the 
articles  to  be  united  and  this  causes  deformation, 
hence  the  necessity  for  considerable  working  of  the 
metal  after  welding. 


WELDING  H 

(2)  Large  quantity  of  heat  wasted,  rendering  the 
process  costly. 

(3)  Difficulty  of  insuring  uniform  success  and  im- 
possibility of  exact  control. 

Forge  welding  is  done,  where  possible,  by  joining 
the  two  sections  after  the  edges  or  ends  have  been 
beveled,  known  as  a  scarf  weld.  This  increases  the 
surface  in  contact  and  the  strength  of  the  joint.  The 
strength  of  these  welds  very  seldom  exceeds  70  per 
cent  of  the  original  strength  of  the  metal. 

The  enlongation  of  forge  welds  is  always  very  low, 
that  is,  the  portion  welded  will  break  apart  before 
stretching  to  any  extent  under  strain.  From  the  point 
of  view  of  brittleness,  forge  welds  show  a  very  low 
average  of  results,  and  frequently  in  tests  under  shock, 
separation  takes  place  at  the  weld.  The  results  ob- 
tained are  notably  inferior  to  those  obtained  with 
well-executed  oxy-acetylene  welds. 

Welding  by  Water  Gas. — This  constitutes  a  more 
perfect  form  of  forge  or  fire  weld.  Instead  of  raising 
the  edges  to  be  joined  to  a  welding  heat  by  fire,  they 
are  submitted  to  the  action  of  a  blowpipe  fed  by  water 
gas.  This  gas  is  chosen  because  it  can  be  produced 
on  the  spot  very  economically.  It  is  made  by  pass- 
ing steam  over  red-hot  coke,  and  consists  of  carbon 
monoxide  and  hydrogen,  which  produce  a  very  high 
temperature  by  their  combustion.  Pneumatic  tools 
rapidly  hammer  the  two  edges  of  the  weld  when  they 
have  been  raised  to  a  welding  heat  by  the  flame. 

Welding  by  water  gas  necessitates  a  very  costly  in- 
stallation, and  does  not  pay  unless  it  is  used  continu- 
ously on  a  very  large  scale.  It  is  not  practically  ap- 
plicable unless  the  plates  have  a  thickness  of  at  least 
-f^  inch. 


12  OXY- ACETYLENE   WELDING  AND  CUTTING 

Thermit  Welding. — This  process  is  only  applicable 
to  the  joining  of  iron  and  mild  steels  of  considerable 
thickness.  It  consists  essentially  in  burning  in  a 
crucible  a  mixture  of  powdered  aluminum  and  iron 
oxide.  The  temperature  of  combustion  is  excessively 
high,  and  can  attain  3000°  C.  (or  over  5400°F.).  The 
aluminum  unites  with  the  oxygen  to  form  alumina, 
while  the  iron  which  is  set  free  accumulates  in  a 
molten  state  at  the  bottom  of  the  crucible. 

This  is  made  to  flow,  by  the  aid  of  a  suitable  mould, 
round  the  parts  to  be  joined,  and  its  temperature  is 
high  enough  to  melt  the  edges  to  be  joined;  thus  a 
weld  which  might  be  called  autogenous  is  obtained. 

It  will  be  understood  that  the  process,  which  re- 
quires costly  material,  can  only  be  used  for  important 
or  repetition  work.  It  has  chiefly  been  used  for  the 
welding  of  rails  and  the  repair  of  very  large  steel  cast- 
ings. Oxy-acetylene  welding  is  largely  replacing  it. 

Brazing. — Brazing  is  accomplished  by  the  use  of  a 
metallic  cement,  melting  at  a  high  temperature  and 
possessing  a  high  mechanical  strength.  Given  these 
facts,  one  can  see  that  it  is  necessary  to  heat  strongly 
the  edges  to  be  joined  and  to  use  a  cleaning  flux  melt- 
ing at  a  high  temperature. 

The  metallic  cement  used  is  called  brazing  metal, 
and  can  be  applied  in  the  form  of  a  powder,  paste,  fil- 
ings, or  grains  often  mixed  with  the  flux.  Its  melt- 
ing point  is  just  below  that  of  the  metal  to  be  joined, 
so  that  in  heating  the  pieces  to  be  brazed,  the  brazing 
metal  melts  and  adheres  to  the  edges  to  be  joined 
when  they  reach  a  high  temperature,  thus  even  form- 
ing an  intermediate  alloy,  and  the  joining  is  obtained 
simply  by  cooling. 

When  it  is  a  question  of  joining  end  to  end  or  edge 


WELDING 


13 


to  edge,  the  brazing  is  done  with  bevelled  faces  placed 
side  by  side.  It  is  clear  that  this  increase  of  suriace 
in  contact  increases  the  resistance  of  the  joint. 

Brazing  necessitates  the  use  of  a  forge  or  blowpipe. 
The  use  of  a  forge  is  costly,  inconvenient,  and  cannot 
be  applied  to  articles  of  all  brass  composition  owing 
to  liability  of  burning  the  metal.  However  the  use 
of  blowpipes  giving  high  temperatures,  oxy-acetylene 
for  example,  makes  possible  the  use  of  brazing  metals 
that  are  less  fusible ;  for  instance,  red  copper  in  join- 
ing pieces  of  cast  iron.  Brazing  seldom  fulfills  the 
conditions  required  for  perfect  joining  of  metal  pieces. 
The  following  are  the  principal  disadvantages  per- 
taining to  brazing : 

(1)  The  part  brazed  possesses  a  different  color  to 
that  of  the  metal. 

(2)  This    same    portion    has    different    chemical, 
physical   and  mechanical  properties  from  the  other 
metal  and  may,  little  by  little,  disintegrate. 

TABLE  I 

COMPOSITION   AND   APPLICATION    OF  BRAZING   METALS 


Application. 

Composition. 

Copper. 

Zinc. 

Malle- 
able 
Brass. 

Silver. 

Gold. 

*5 
4 

For  copper,    brass,   iron.... 
For   copper,    brass,   iron.... 
For  copper  (very  fusible)  .  . 
For    turning    brass     . 

2 

50 
45 
1.5 
1 

1 
1 

48 
45 
6 

5 

io 

1 

1 
1 
1 

'2 
10 

19 
2 

1 
5 
67 

For  steel           

For    plates    

For  copper  or  iron..  

Fusible    solder    

1 
10 

For  silver  (950  parts  in  1000) 
For    gold    

23 
1 

For  gold  (750  parts  in   1000) 

1 

1 

14  OXY-ACETYLENE  WELDING  AND  CUTTING 

Blowpipe  Welding. — Blowpipe  welding  consists  in 
uniting  the  metal  pieces  by  means  of  a  flame  of  ap- 
propriate temperature  with  the  addition  of  metal  of 
the  same  composition.  The  joint  thus  obtained  is 
called  autogenous. 

Strictly  speaking,  the  welds  obtained  by  the  fire, 
water  gas,  or  electricity  can  be  called  autogenous, 
since  they  have  been  obtained  without  the  interposi- 
tion of  a  metallic  cement  whose  properties  differ  from 
that  of  the  metal  joined. 

In  current  language  the  name  autogenous  welds  is 
understood  to  mean  those  which  are  obtained  by  melt- 
ing the  metal  under  the  action  of  the  flame  of  a  blow- 
pipe. 

The  blowpipe  is  an  instrument  in  which  the  flame 
is  produced  and  projected  on  to  the  metallic  parts  to 
be  welded. 

Blowpipe  welding  has  been  known  for  a  long  time, 
at  least  for  the  joining  of  metals  whose  melting-point 
is  not  very  high,  and  was  easily  obtained  by  com- 
bustible gases  burning  in  air  or  in  a  current  of  air. 
The  autogenous  welding  of  lead  was  thus  obtained  by 
the  Egyptians,  the  Greeks,  and  the  Romans. 

The  autogenous  welding  of  metals  with  high  melt- 
ing-points was  not  possible  until  the  industrial  manu- 
facture of  oxygen  permitted  the  use  of  this  gas  for 
the  production  of  flames  of  high  temperature. 

First  of  all  the  oxy-hydrogen  (oxygen  and  hydro- 
gen) flame,  then  the  oxy-acetylene  (oxygen  and  acet- 
ylene) were  thought  of.  After  these  oxy-coal  gas 
(oxygen  and  coal-gas),  oxy-benzene  or  oxy-benz  (oxy- 
gen and  vapour  of  benzol),  etc. 

Autogenous  welding  by  means  of  the  blowpipe  is 
the  process  that  has  been  most  developed  in  recent 


WELDING  15 

years.  This  is  proved  by  its  use  in  the  majority  of 
work  shops  for  construction  and  repairs.  The  one 
defect  in  connection  with  blowpipe  welding  is  that, 
owing  to  the  apparent  ease  with  which  the  work  is 
done,  it  is,  in  many  cases,  applied  by  persons  who  have 
made  no  previous  study  of  its  requirements.  Proper 
care  is  not  used  in  the  work  and  the  result  is  many 
failures. 

Welding  at  the  forge,  brazing,  or  even  soldering,  all 
require  special  knowledge  on  the  part  of  the  operator 
in  order  that  he  may  be  able  to  do  reliable  work.  The 
easy  appearance  of  blowpipe  welding  often  leads  an 
unskilled  workman  to  attempt  to  do  a  job  which, 
while  often  appearing  perfect  on  the  outside,  is  de- 
fective and  unsafe. 

ADAPTABILITY  OF  VARIOUS  SYSTEMS  OF  BLOWPIPE 
WELDING 

The  manufacturer  or  workman  who  wishes  to  apply 
autogenous  welding  should  study  the  various  systems 
which  are  offered,  and  find  which  gives  him  the  most 
advantages. 

The  principal  points  to  which  he  should  direct  his 
attention  are  the  following : — Adapting  the  System  to 
the  Type  of  Work;  Safety;  Quality  of  Work;  Econ- 
omy; Convenience;  Cost  of  Material. 

Adapting  the  System  to  the  Type  of  Work. — When 
a  process  is  no  longer  applicable  to  the  work  under 
consideration  all  interest  in  the  process  lapses.  In 
reality,  the  value  or  economy  of  any  particular  system 
of  blowpipe  welding  depends  upon  the  type  of  work. 
Among  the  processes  enumerated,  it  is  first  of  all 
necessary  to  discern  which  is  best  applicable  to  the 
type  of  work. 


16  OXY-ACETYLENE  WELDING  AND  CUTTING 

Safety. — It  can  be  considered  that  all  the  processes 
of  blowpipe  welding  have  been  sufficiently  studied  and 
developed  as  not  to  offer  any  serious  danger  if  the 
usual  precautions  are  observed.  The  systems  using 
benzol  or  other  combustible  liquids  have  become  safe, 
and  are  practically  free  from  danger. 

Quality  of  Work. — The  quality  of  the  work  pro- 
duced by  blowpipe  welding  is  not  the  same  in  all  sys- 
tems.    According  to  the  metal  and  its  thickness,  the 
weld  may  be  more  or  less  well  finished  and  sound,  and 
a  process  which  may  be  satisfactory  in  one  case  may 
not  prove  so  in  another.    It  is  therefore  necessary  th 
each  system  should  be  kept  in  its  particular  sphere 
usefulness. 

Economy. — The  factor  of  economy  may  differ  ac- 
cording to  the  application  of  autogenous  welding  con- 
templated.    In  certain  cases  the  cost  of  the  work  * 
of  first  importance,  while  in  other  cases  this  may  be 
a   secondary  consideration.     A  certain  process  ^ 
appear  to  be  economical  and  yet  be  expensive,  or 
economical  under  certain   conditions   or   for  certain 
welds  and  not  for  others.    The  question  of  the  net  cost 
of  welding  must  be  considered  with  reference  to  the 
quality  of  work  and  convenience. 

Convenience. — Convenient  application  is  important 
in  the  choice  of  a  method  and  should  be  carefully 
studied  from  all  points  of  view,  such  as  installation, 
maintenance,  supervision,  etc.  A  system  which  seen, 
to  offer  great  simplicity  and  convenience  may  not 
prove  so  in  practice.  Good  judgment  is  therefore 
necessary,  followed  by  a  comparison  of  the  different 
methods  with  reference  to  the  kinds  of  work  to  be 
done. 

Cost  of  Material. — The  various  systems  of  blowpipe 


WELDING  17 

welding  do  not  have  the  same  purpose  in  view,  and 
the  importance  that  is  attached  to  some  of  them  is 
only  on  account  of  the  facility  and  economy  of  their 
installation.  They  may  be  applicable  where  others  are 
not,  and  it  is  only  from  this  point  of  view  that  they 
deserve  attention. 

On  the  other  hand  when  it  is  a  question  of  regular 
or  important  work,  the  question  of  first  costs  will  not 
be  so  important,  the  extra  cost  of  material  being  soon 
recovered  owing  to  more  economical  working,  greater 
convenience  and  better  results. 


CHAPTER  II 

WELDING  FLAMES 
OXY-ACETYLENE   FLAME 

Although  oxy-hydrogen  welding  was  proposed 
before  oxy-acetylene,  the  latter  process  is  by  far  the 
most  common  and  will  therefore  serve  as  a  basis  for 
comparison  with  others.  The  first  blowpipes  working 
with  acetylene  under  pressure  were  made  in  1901  by 
MM.  Fouche  and  Picard.  From  1903  it  has  been 
applied  industrially,  and  the  progress  has  been  ex- 
tremely rapid. 

In  1895  M.  Le  Chatelier,  in  a  paper  read  before  the 
Academic  des  Sciences  on  the  temperature  of  flames, 
stated  that  ' '  acetylene  burnt  with  an  equal  volume  of 
oxygen  gives  a  temperature  which  is  1832°  Fahr. 
higher  than  the  oxy-hydrogen  flame.  The  products 
of  the  combustion  are  carbon  monoxide  and  hydrogen, 
which  are  reducing  agents ";  and  the  paper  concluded 
with  this  sentence :  '  '  This  double  property  makes  the 
use  of  acetylene  in  blowpipes  of  very  great  value  for 
the  production  of  high  temperatures  in  the  labora- 
tory." 

As  was  first  pointed  out  by  M.  Chatelier,  the  oxy- 
acetylene  flame  results  from  the  combustion  of  a  mix- 
ture of  oxygen  and  acetylene  in  equal  volumes.  Theo- 
retically it  requires  2%  volumes  of  oxygen  to  com- 
pletely burn  1  volume  of  acetylene,  and  this  is  actually 
what  takes  place  if  one  takes  into  account  the  oxygen 
taken  from  the  air  during  the  last  phase  of  the  com- 
bustion ;  but  the  blowpipe  need  only  supply  the  oxygen 

18 


WELDING  FLAMES  19 

necessary  to  form  the  white  welding  jet,  and  for  this 
the  volume  is  exactly  1  to  1. 

In  practice,  however,  the  volumes  are  in  the  ratio  of 
1.28  to  1.13  of  oxygen  for  1  of  acetylene,  owing  to  the 
fact  that  the  mixture  of  the  two  gases  is  not  abso- 
lutely perfect.  Below  are  given  the  chemical  formulae 
and  equations  representing  oxy-acetylene  combustion. 

Burnt  with  an  equal  volume  of  oxygen,  acetylene 
produces  hydrogen  and  carbon  monoxide  : — 


Acetylene  and  oxygen  yield  hydrogen  and  carbon 
monoxide. 

The  hydrogen  and  oxide  next  burn,  taking  the 
necessary  oxygen  from  the  air  and  producing  water 
vapor  and  carbon  dioxide  : — 

CO  +  O  =  C02. 

Carbon  monoxide  and  oxygen  yield  carbon  dioxide. 

Hydrogen  and  oxygen  yield  water  vapor. 

The  carbon  monoxide  formed  in  the  first  part  of  the 
combustion  is  therefore  entirely  burnt  in  the  second, 
and  it  could  not  be  otherwise  unless  one  deprived  the 
flame  of  air.  A  paper  by  M.  Mauricheau-Beaupre  to 
the  Academic  des  Sciences  in  January  1906  describes 
a  series  of  tests  which  point  to  the  complete  absence 
of  carbon  monoxide  in  the  atmosphere  surrounding  the 
oxy-acetylene  flame.  Poisoning  of  welders  has  there- 
fore never  existed  other  than  in  the  imagination  of 
manufacturers  of  blowpipes  for  gases  other  than  acet- 
ylene. 

The  combustion  of  1  cubic  foot  of  acetylene  pro- 
duces 410  calories,  or  1630  British  Thermal  Units, 
nearly  five  times  as  much  as  that  of  hydrogen  and 
three  times  as  much  as  oil  gas.  Of  these,  68  calories, 


20  OXY- ACETYLENE  WELDING  AND  CUTTING 

or  270  B.T.U.,  are  due  to  the  heat  of  dissociation  of 
the  acetylene,  which  is  an  endothermic  gas,  and  dis- 
engaging suddenly  at  the  moment  of  its  decomposi- 
tion, explains  the  very  high  temperature  at  the  begin- 
ning of  the  flame.  It  should  be  noted  that  the  other 
gases  which  are  used  in  autogenous  welding  do  not 
possess  this  property. 

Temperature. — The  temperature  of  the  oxy-acety- 
lene  flame,  taken  at  the  extremity  of  the  white  jet  is 
very  much  higher  than  that  of  any  other  flame.  It  is 
estimated  to  equal  6500°  Fahr.  The  white  jet  of  this 
flame  will  in  cases  melt  lime,  the  melting  point  of 


Figure  1. — Phases  of  the  Combustion  in  the  Oxy-acetylene  Flame 

which  is  5400°  Fahr.,  and  this  can  only  be  obtained 
otherwise  in  the  electric  arc. 

Combustion. — The  final  products  of  combustion  are 
carbon  dioxide  and  water  vapor,  the  latter  in  less 
quantity  than  for  the  oxy-hydrogen  flame,  but  the 
molten  metal,  under  the  action  of  the  flame  only  comes 
in  contact  with  the  carbon  monoxide  and  hydrogen 
produced  in  the  first  stage  of  combustion,  since  the 
wrelding  is  done  at  the  extremity  of  the  white  jet. 

These  gases,  which  have  the  property  of  taking  care 
of  any  excessive  oxygen  and  avoiding  burnt  metal, 
form  a  flame,  which  when  properly  proportioned,  have 
but  little  effect  on  the  characteristics  of  the  metal. 
This  flame  is  said  to  be  neutral.  Figure  1  shows  in  a 


-WELDING  FLAMES  21 

graphic  manner  the  phases  of  combustion  in  the  oxy- 
acetylene  flame. 

Utilization  of  the  Heat. — The  coefficient  of  utiliza- 
tion is  very  high  in  the  case  of  the  oxy-acetylene  flame 
because  the  highest  temperature  is  concentrated  at  the 
point  of  the  welding  flame,  the  white  jet. 

Regulation. — The  regulation  of  the  blowpipe  is  ac- 
complished with  the  greatest  ease,  and  neither  their 
working  nor  their  manufacture  offers  any  difficulties. 
They  are  constructed  for  all  deliveries  from  1%  to  140 
cubic  feet  of  acetylene  gas  per  hour,  and  in  all  well 
designed  installations  absolute  safety  is  assured. 

OXY-HYDROGEN  FLAME 

The  first  oxy-hydrogen  blowpipe  appears  to  have 
been  suggested  by  Robert  Hare  of  Philadelphia  about 
the  year  1805.  In  1820  Brooke,  in  Germany,  designed 
an  arrangement  by  which  a  mixture  of  oxygen  and 
hydrogen,  previously  compressed  by  means  of  a  force- 
pump  into  a  strong  plate  vessel,  escaped  by  a  capillary 
tube  of  glass.  When  the  extremity  of  this  tube  melted 
or  became  stopped  up,  it  was  only  necessary  to  break 
off  a  small  portion  to  set  it  in  working  order  again. 

This  type  of  blowpipe,  the  manipulation  of  which 
was  dangerous  because  of  pre-mixing  of  the  two  gases, 
was  first  modified  by  Berzelius.  Next  Pius  Sainte- 
Claire  Deville  made  a  blowpipe,  using  oxygen  and 
hydrogen  compressed  in  two  separate  vessels.  He  suc- 
ceeded in  melting  iron,  silver,  .and  platinum. 

The  oxy-hydrogen  blowpipe  remained  a  laboratory 
instrument  until  such  time  as  the  gases  could  be  pro- 
duced at  a  low  price  and  arrangements  devised  for 
their  safe  storage. 

It  was  first  introduced  for  industrial  autogenous 


22  OXY-ACETYLENE  WELDING  AND  CUTTING 

welding  in  1901.  The  oxy-hydrogen  flame  is  produced 
by  the  combination  of  two  volumes  of  hydrogen  with 
one  volume  of  oxygen,  forming  water  vapor.  The 
chemical  expression  follows: 

H2  +  0  =  H20. 

Hydrogen  and  Oxygen  yield  Water  Vapor. 

In  the  first  applications  to  autogenous  welding  it 
was  found  that  the  water  vapor  which  is  produced 
exclusively  and  abundantly,  provoked  considerable 
oxidation  of  the  metal  when  raised  to  melting  point 
or  simply  heated,  and  that  all  serious  joining  was 
impossible.  The  only  artifice  possible  was  to  dilute 
the  water  vapor  with  an  excess  of  hydrogen,  and  in 
order  to  produce  good  welds,  it  was  necessary  to  raise 
the  proportion  of  the  gases  from  2  to  4  volumes  of 
hydrogen,  for  1  volume  of  oxygen,  and  this  is  what  has 
been  done  in  practical  applications. 

The  oxy-hydrogen  flame  used  in  autogenous  welding 
results  from  the  combustion  of  a  mixture  of  4  volumes 
of  hydrogen  and  1  of  oxygen,  half  the  hydrogen  used 
serving  to  dilute  the  water  vapor  formed  at  the  begin- 
ning of  the  reaction,  then  burning  afterwards  in  oxy- 
gen borrowed  from  the  air. 

It  is  understood  that  in  spite  of  the  artifice  of  using 
excess  hydrogen,  the  disadvantage  of  oxidation  of  the 
metal  by  the  water  vapor  still  exists  in  part,  because 
diluting  this  water  vapor  does  not  get  rid  of  it.  The 
metal,  during  welding,  heated  or  melted,  is  always 
therefore  in  contact  with  an  atmosphere  which  is  less 
neutral  than  in  the  case  of  acetylene. 

One  cubic  foot  of  hydrogen  produces  88  calories, 
equal  to  350  British  thermal  units  (abbreviated 
B.T.U.).  One  cubic  foot  of  acetylene  produces  410 
calories,  equal  to  1630  B.T.U. 


WELDING  FLAMES  23 

Temperature. — For  the  same  number  of  heat  units, 
the  oxy-hydrogen  fiarne  is  less  in  volume  than  the  oxy- 
acetylene  flame,  the  heat  is  less  easily  utilized  for 
obtaining  autogenous  welds  owing  to  the  fact  that  the 
high  temperature  zone  is  not  so  well  localized.  Neither 
is  the  temperature  as  high,  since  it  never  exceeds  4200° 
Fahr. 

Uses  of  Oxy-Hydrogen  for  Welding. — Since  it  is 
difficult  with  oxy-hydrogen  blowpipes  to  melt  the 
edges  to  be  welded,  even  in  thin  pieces,  it  is  practically 
impossible  to  make  satisfactory  welds  of  steel  exceed- 


Figure  2. — Oxy-hydrogen  Blowpipe  Working:  with  the  Gases 
Pre- mixed 

ing  *4  inch  in  thickness.  Its  use  is  therefore  limited 
to  work  up  to  about  ^  inch  in  the  case  of  iron  or 
steel.  Even  within  these  limits  the  welds  are  not  as 
good  and  cost  more  than  oxy-acetylene  welds.  The 
cost  of  the  installation  differs  but  little  from  that  of 
an  oxy-acetylene  plant.  A  considerable  amount  of 
practice  is  required  to  enable  the  workman  to  properly 
regulate  the  oxy-hydrogen  blowpipe.  Figure  2  shows 
the  type  of  blowpipe  used  in  this  process. 

OTHER  GAS  FLAMES 

Oxy-Coal  Gas. — This  term  is  given  to  the  flame  pro- 
duced by  the  combustion  of  a  mixture  of  oxygen  and 


24  OXY- ACETYLENE  WELDING  AND  CUTTING 

illuminating  gas.  In  1838  Debassyns  de  Richemont 
replaced  the  hydrogen  in  an  oxy-hydrogen  blowpipe 
with  coal  gas.  Brazed  joints  and  autogenous  welds  in 
lead  were  obtained  with  the  flame  thus  produced. 
When  the  oxy-hydrogen  and  oxy-acetylene  processes 
became  known  industrially,  due  to  the  production  of 
oxygen  at  a  low  price,  the  use  of  coal  gas  for  obtain- 
ing autogenous  welds  was  again  considered.  The 
process  was  tempting  because  it  made  a  cheap  and 
easy  installation  possible  in  any  workshop  supplied 
with  gas. 

Welding  by  oxy-coal  gas  has  not  had  and  cannot 
have  a  very  wide  application  as  can  be  easily  shown. 
Illuminating  gas  is  a  mixture  of  various  gases  and  its 
composition  is  not  absolutely  constant.  One  cubic  foot 
of  average  quality  contains  about : — 

0.5     cubic  foot  of  hydrogen. 

0.35  cubic  foot  of  methane. 

0.08  cubic  foot  of  carbon  monoxide. 

0.02  cubic  foot  of  carbon  dioxide. 
The  combustion  of  one  cubic  foot  of  this  gas  pro- 
duces 600  to  750  B.T.U.  The  temperature  of  the 
oxy-coal  gas  flame  is  no  higher  than  that  of  the  oxy- 
hydrogen  flame  and  the  utilization  of  the  heat  is  no 
better.  Further  it  gives  results  that  are  decidedly 
bad  from  the  viewpoint  of  the  quality  of  the  weld. 

It  has  been  shown  that  in  oxy-hydrogen  welding  the 
strong  oxidation  of  the  metal  can  only  be  avoided  by 
diluting  the  water  vapor  produced  with  a  large  excess 
of  hydrogen.  The  oxy-coal  gas  flame  produces  as 
much  water  vapor  as  the  oxy-hydrogen  flame,  and 
therefore  one  should  follow  the  same  procedure.  But, 
apart  from  the  disadvantages  produced  by  an  excess 
of  coal-gas  in  the  flame,  it  would  not  be  possible  to 


WELDING  FLAMES  25- 

introduce  an  appreciable  excess  on  account  of  its  low 
pressures.  Unlike  hydrogen  in  the  oxy-hydrogen  pro- 
cess, .the  oxygen  has  to  draw  it  by  suction,  and  the 
quantity  is  necessarily  limited. 

The  welds  obtained  by  oxy-coal  gas  blowpipes  are 
therefore  always  very  strongly  oxidized  and  excessively 
fragile,  so  that  their  resistance  is  practically  nil.  In 
fact,  oxy-coal  gas  welds  should  be  prohibited  in  all 
cases  where  the  work  is  likely  to  be  subject  to  strains, 
and  little  recommended  for  joints  which  do  not  require 
to  be  strong  or  tight.  In  iron  and  steel  work  one  can 
only  apply  it  on  thin  material. 

The  style  of  blowpipe  used  in  this  system  is  shown 


Figure  3. — Oxy-coal  Gas  Blowpipe 


in  Figure  3.  It  should  also  be  noted  that  the  arrange- 
ments for  preheating  the  gases  previous  to  combus- 
tion, with  a  view  to  obtaining  a  higher  temperature  in. 
oxy-coal  gas  or  oxy-hydrogen  flames,  do  not  achieve 
the  desired  result.  This  is  because,  if  the  temperature 
is  increased,  the  water  vapor  dissociates  with  the 
absorption  of  heat,  the  two  elements  recombine  much 
farther  in  the  flame,  thus  giving  back  their  heat  of 
formation,  but  which  has  already  been  absorbed. 

Oxy-Benz. — The  term  "oxy-benz"  has  been  adopted 
to  describe  welding  flames  produced  by  the  combus- 
tion of  mixtures  of  oxygen  and  the  vapors  of  benzine, 
benzol,  gasoline,  and  all  other  liquid  hydrocarbons. 
While  these  processes  may  prove  to  be  of  value  in 


26  OXY-ACETYLENE  WELDING  AND  CUTTING 

special  cases,  they  are  not  adapted  to  the  ordinary 
applications  of  autogenous  welding.  One  great  defect 
in  oxy-benz  work  is  that  it  involves  the  use  of  a  liquid 
fuel  which  must  first  be  vaporized.  This  operation, 
even  when  semi-automatic,  requires  time  and  care  on 
the  part  of  the  operator  and  regularity  is  very  hard  to 
obtain. 

The  blowpipe,  a  view  of  which  is  shown  in  Figure 
4,  is  a  very  delicate  and  complicated  instrument.  The 
acetylene  generator  or  the  hydrogen  cylinder  used  in 
the  oxy-acetylene  and  oxy-hydrogen  processes  are 
replaced  by  a  vessel  containing  the  liquid,  usually 


Figure  4. — Oxy-benz  Blowpipe 

under  pressure.  The  use  of  a  branch  from  the  oxygen 
for  obtaining  this  pressure  is  attended  by  danger  and 
in  order  to  avoid  risk  of  explosion  it  is  necessary  to  use 
devices  which,  while  being  very  ingenious,  are  ex- 
tremely complicated. 

Conclusions  on  Welding  Flames. — The  great  success 
of  the  oxy-acetylene  welding  process  has  given  rise  to 
various  other  methods  and  will  no  doubt  lead  to  the 
development  of  others.  There  are  for  instance,  liquid 
gas,  Blau  gas,  vulcan  gas,  etc.,  but  acetylene  offers 
many  advantages  over  all  others  so  far  offered,  and  it 
is  the  only  process  by  which  welds  from  the  smallest 
to  the  very  largest  can  be  obtained  while  offering 
assurance  of  strength  in  the  weld. 


WELDING  FLAMES  27 


Oxy-hydrogen  is  inferior  to  the  oxy-acetylene  pro- 
cess, although  giving  better  results  than  oxy-benz 
welding.  Oxy-benz  and  similar  processes  have  no 
value  except  for  special  application's  and  in  cases 
where  the  work  is  not  important  enough  to  justify  an 
oxy-acetylene  installation. 


CHAPTER  III 

OXYGEN 
PROPERTIES  OF  OXYGEN 

Oxygen  is  invariably  the  combustion  agent  used  in 
autogenous  welding  with  the  blowpipe.  It  is  neces- 
sary for  those  using  it  to  be  familiar  with  its  proper- 
ties, manufacture,  storage,  methods  of  use,  etc. 

Oxygen  is,  of  all  bodies,  the  most  widely  distributed 
in  nature.  It  exists  in  a  state  of  mixture  in  the  air, 
which  contains  about  one-fifth  of  its  volume  of  this 
gas.  Water  is  a  compound  of  oxygen  and  hydrogen, 
containing  nearly  89  per  cent  of  the  former  element. 
Oxygen  is  found  in  nearly  all  mineral  and  organic 
substances. 

This  gas  was  isolated  by  Priestley  in  England,  and 
Scheele  in  Sweden.  Lavoisier  studied  its  properties 
and  gave  it  the  name  of  oxygen. 

Physical  Properties. — Oxygen  is  a  colorless,  taste- 
less, and  odorless  gas.  Its  density  is  1.1056. 

One  litre  (about  61  cu.  in.)  of  oxygen  at  32°  Fahr. 
and  atmospheric  pressure  weighs  22.06  grains. 

It  is  not  very  soluble  in  water;  100  volumes  of 
water  at  32°  Fahr.  can  dissolve  nearly  5  volumes  of 
oxygen  at  atmospheric  pressure. 

Formerly,  oxygen  was  considered  a  body  not  capable 
of  existing  in  the  liquid  state.  In  1877  M.  Cailletet 
and  Pictet  succeeded  in  liquefying  it  by  compressing 
it  to  320  atmospheres  and  lowering  its  temperature  to 
220°  Fahr.  below  zero.  In  the  liquid  state  its  density 
approaches  that  of  water.  Like  all  other  gases,  oxygen 
can  be  compressed. 

28 


OXYGEN  29 

Chemical  Properties. — Among  chemists  oxygen  is 
known  by  the  symbol  0.  Its  atomic  weight  is  16. 

The  characteristic  property  of  oxygen  is  its  power 
of  supporting  combustion.  A  glowing  candle  will 
instantly  burst  into  flame  if  plunged  into  a  jar  of 
oxygen. 

Iron  heated  to  redness  burns  in  oxygen. 

The  combustion  is  a  chemical  reaction  between  the 
oxygen  and  the  body  which  burns  in  it.  The  product 
of  the  combustion  is  called  oxide,  and  the  metal  is  said 
to  be  oxidized. 

Under  the  heading  of  combustion  should  also  be 
placed  slow  combustion,  in  which  oxidization  takes 
place  while  the  temperature  of  the  metal  is  not  espec- 
ially high.  Oxidization  of  metals  by  contact  with 
oxygen  or  air  is  slowr  combustion.  The  intensity  of 
this  action  increases  with  the  heat,  which  accounts  for 
the  fact  that  most  metals  oxidize  rapidly  when  red 
hot  in  air  and  of  course  much  more  rapidly  when  in 
contact  with  pure  oxygen. 

Manufacture  of  Oxygen. — Oxygen  is  usually  pre- 
pared in  the  laboratory  by  heating  manganese  dioxide 
to  bright  red  heat  which  causes  it  to  give  up  one-third 
of  its  oxygen ;  or  by  heating  potassium  chlorate  which 
likewise  gives  up  its  oxygen.  If  the  potassium  chlorate 
is  mixed  with  about  one-eighth  its  weight  of  man- 
ganese dioxide,  the  action  is  much  more  regular. 
These  processes  are  not  commercially  useful.  They 
were  used  when  oxygen  could  not  be  secured  in  any 
other  way.  It  is  due  to  the  manufacture  of  oxygen  at 
a  low  price  that  autogenous  welding  has  developed, 
and  this  development  has  stimulated  inventors  and 
manufacturers  to  search  for  processes  or  improve- 


30  OXY-ACETYLENE  WELDING  AND  CUTTING 

ments  which  would  produce  oxygen  at  still  lower 
prices. 

Electrolysis  of  Water. — Water  is  composed  of 
hydrogen  and  oxygen  and  may  be  divided  into  these 
elements,  the  two  gases  being  collected  separately.  This 
operation  is  easily  carried  out  by  means  of  electricity 
and  is  called  electrolysis.  Water,  to  which  a  small 
quantity  of  sulphuric  acid  or  potash  has  been  added, 
is  treated  with  an  electric  current  in  an  electrolizer. 
The  oxygen  comes  from  the  negative  pole  and  the 
hydrogen  from  the  positive  pole.  The  gases  are  then 
collected  separately  and  conveyed  to  gasometers.  The 
hydrogen  is  used  for  oxy-hydrogen  welding,  filling 
balloons,  etc.  Oxygen  made  by  this  process  is  gen- 
erally very  pure,  but  the  electrolizers  require  great 
care  and  much  supervision  to  avoid  mixtures  of  the 
two  gases,  such  mixtures  being  extremely  dangerous. 
This  risk  has  been  greatly  diminished  in  recent  years 
by  the  use  of  automatic  indicators  which  give  an 
alarm  in  case  of  the  diffusion  of  the  oxygen  and  hy- 
drogen. 

The  process  is  considered  more  costly  than  that  of 
extracting  the  oxygen  from  the  air,  but  according  to 
the  scale  of  production  and  the  general  conditions  of 
working  it  may  compete  with  it. 

Extraction  of  Oxygen  from  the  Air. — Attempts 
were  made  long  ago  to  extract  oxygen  from  the  air, 
where  it  exists  as  a  simple  mixture  with  nitrogen 
(nitrogen  79  per  cent,  oxygen  21  per  cent). 

A  mechanical  treatment  of  air  rich  in  oxygen  was 
tried,  but  a  complete  separation  of  the  two  gases  was 
not  possible.  This  process  was  abandoned,  but,  with- 
out doubt,  the  last  word  has  not  been  said,  and  there 


OXYGEN  31 

is  still  the  possibility  of  it  being  applied  industrially 
some  day. 

Boussingault  devised  a  method  for  the  extraction  of 
the  oxygen  from  the  air  which  is  still  being  used, 
although  going  out  of  use.  It  consists  in  gently  heat- 
ing baryta  (BaO)  to  dull  redness  in  air.  The  oxygen 
combines  with  the  baryta  forming  the  dioxide  (Ba02), 
but  at  a  bright  red  heat  this  parts  with  the  additional 
oxygen  with  the  reproduction  of  baryta.  By  thus 
alternately  varying  the  temperature  a  regular  produc- 
tion of  gas  can  be  obtained. 

The  process  of  Mothay  and  Marechal  consisted  in 
passing  air  over  a  heated  mixture  of  manganese 
dioxide  and  soda.  The  substance  absorbs  the  oxygen 
and  is  converted  into  manganate.  Water  vapor  is  then 
passed  over  the  manganate  to  decompose  it,  that  is,  to 
liberate  the  oxygen  which  it  has  absorbed,  which  regen- 
erates the  mixture  of  manganese  dioxide  and  soda. 

During  the  last  few  years  the  economical  production 
of  oxygen  has  been  obtained  by  the  liquefaction  of  air 
and  the  separation  into  its  two  constituents. 

Professor  Linde  was  the  first  to  work  out  an  indus- 
trial arrangement  for  the  liquefaction  of  air,  and  for 
the  separation  of  the  liquid  into  two  constituents,  oxy- 
gen and  nitrogen.  Claude,  Pictet,  Levy,  and  Hel- 
bronner,  completed  the  problem,  and  designed  ex- 
tremely ingenious  plants  for  the  economical  produc- 
tion of  liquid  air  and  its  rational  distillation. 

We  can  only  give  the  main  outlines  of  the  opera- 
tions. The  air  to  be  liquefied  is  first  compressed,  then 
expanded.  This  lowers  its  temperature  and  ultimately 
reaches  liquefaction. 

Although  the  oxygen  and  the  nitrogen  liquefy  simul- 
taneously, Claude  succeeded  in  obtaining  the  first  jet 


32  OXY-ACETYLENE  WELDING  AND  CUTTING 

of  liquid  rich  in  oxygen,  which,  by  a  process  of  recti- 
fication, gets  rid,  little  by  little,  of  its  nitrogen.  The 
Linde  process  consists  of  the  fractional  distillation  of 
liquid  air,  which  brings  about  the  production  of  pure 
oxygen.  Other  plants  have  been  designed  besides 
these,  iising  more  or  less  these  two  systems  or  their 
combination,  hence  the  patents  and  claims  of  these  are 
contested  by  the  others. 

As  a  general  conclusion  one  might  say  that  the 
liquid  air  process  is  the  most  economical.  It  is  also 
the  one  that  has  been  most  developed.  Obtaining 
economical  autogenous  welds  is  the  result  of  the  re- 
duction of  price  in  oxygen  due  to  the  successful  pro- 
duction of  oxygen  from  the  air. 

Other  Processes. — Other  processes  for  the  produc- 
tion of  oxygen  for  industrial  use  have  been  invented 
and  used  with  varying  degrees  of  success.  The  use 
of  potassium  perchlorate  is  an  improvement  over  the 
older  methods,  especially  as  this  body  is  made  to  give 
up  the  greater  part  of  its  oxygen  by  auto-combustion. 
It  forms  the  basis  of  a  product  known  as  oxygenite. 

Oxygenite  is  a  yellow  substance  of  sandy  appear- 
ance. It  is  unaffected  by  air  and  does  not  deteriorate 
if  stored  in  a  dry  place.  A  special  apparatus,  a  sec- 
tional elevation  of  which  is  shown  in  Figure  5,  is  used 
for  the  combustion  and  the  storing  of  the  oxygen 
under  pressure.  It  is  only  necessary  to  place  the 
product  in  a  chamber  for  the  purpose,  introduce  it 
into  the  apparatus  as  shown  at  the  top  of  Figure  5, 
light,  then  close  the  gas-tight  cover.  After  a  few 
minutes  oxygen  is  produced  under  pressure.  One 
pound  of  oxygenite  supplies  about  four  cubic  feet  of 
oxygen.  The  cost  of  oxygen  produced  in  this  way  is 
much  higher  than  the  price  of  oxygen  produced  from 


OXYGEN 


33 


air  or  by  electrolysis  from  water.  The  only  advantage 
connected  with  the  oxygenite  process  is  that  its  use 
makes  it  possible  to  produce  the  oxygen  at  the  place 


Figure  5. — Apparatus  for  the  Production  of  Oxygen  from 
Oxygenite 

of  consumption  and  in  localities  far  from  oxygen  pro- 
ducing works. 

The  cost  of  renting  and  the  transportation  of  the 
steel  cylinders  in  which  compressed  oxygen  is  sold, 
makes  their  use  impossible  in  places  far  removed  from 


34  OXY-ACETYLENE  WELDING  AND  CUTTING 

industrial  centers  and  in  these  places  oxygenite  may 
render  valuable  service. 

Another  method  of  obtaining  oxygen  is  by  the  use 
of  epurite,  a  mixture  of  chloride  of  lime,  iron  sulphate 
and  copper  sulphate.  This  mixture  is  soaked  in 
water,  when  the  generation  of  gas  takes  place  slowly. 
This  is  a  more  costly  process  than  the  oxygenite 
method. 

Oxygen  from  Chlorate  of  Potash. — An  apparatus 
for  generating  oxygen  from  chlorate  of  potash  con- 
sists of  a  furnace  lined  with  fire  brick,  containing  a 
gas  or  coal  burner  and  an  air-tight  cast  iron  retort, 
cast  iron  buckets,  scrubbers,  gasometer,  water  cooled 
compressor,  high  pressure  tanks  and  gauges. 

To  extract  oxygen  from  chlorate  of  potash  a  small 
quantity  of  manganese  dioxide  is  mixed  with  the 
chlorate  and  placed  in  a  cast  iron  bucket;  this  is  put 
into  an  air-tight  retort  of  cast  iron  fitted  in  the  fur- 
nace and  heated  until  the  oxygen  is  driven  out.  The 
pressure  thus  created,  forces  the  oxygen  through  the 
scrubbers  which  separate  it  from  the  chlorine  gas  and 
purify  the  oxygen.  Pure  oxygen  is  very  necessary  to 
obtain  a  perfect  welding  flame.  From  the  scrubbers 
the  gas  enters  the  gasometer  from  which  it  is  drawn 
by  the  compressor  and  forced  into  the  pressure  tanks ; 
from  these  tanks  it  is  let  into  the  line  as  required  by 
means  of  valves.  By  this  process  it  is  claimed  that 
oxygen  cf  99  per  cent  purity  is  obtained.  The  appa- 
ratus also  possesses  the  advantage  of  being  easily 
installed  in  any  locality. 

OXYGEN  IN  CYLINDERS 

Oxygen  extracted  from  the  air  or  secured  by  the 
electrolysis  of  water  is  delivered  from  the  works  in 


OXYGEN  35 


steel  cylinders  under  a  pressure  of  about  1800  pounds 
to  the  square  inch.  These  cylinders,  tubes  or  bottles, 
as  they  are  variously  called,  may  be  studied  with 
advantage.  They  are  constructed  of  steel.  Figure  6 


Figure    6. — Section    of    Oxygen    Cylinder 

shows  a  section  of  one  of  them.  The  walls  are  of  suf- 
ficient thickness  to  withstand  a  much  higher  pressure 
than  that  to  which  the  oxygen  is  compressed.  The 
cylinders  are  tested  by  a  hydraulic  apparatus  to  twice 
the  working  pressure  or  about  5000  pounds  per  square 
inch.  Oxygen  can  not  be  divided  into  other  gases,  its 


36  OXY-ACETYLENE  WELDING  AND  CUTTING 

use  is  therefore  safe  from  danger  of  explosive  burning. 
The  base  of  the  oxygen  cylinder  may  be  encased  in  a 
stand,  enabling  the  cylinder  to  be  placed  upright  and 
preventing  sudden  shocks  during  manipulation.  The 
top  of  the  cylinder  is  dome  shaped  and  terminates  in 
•a  threaded  portion  inside  of  which  the  cylinder  valve 
is  carried  and  over  which  may  be  screwed  a  protect- 
ing cap  which  entirely  covers  the  valve  stem  and 
handle. 

Compression  of  Gas  into  Cylinders. — The  oxygen 
when  obtained  is  stored  in  large  tanks,  or  gasometers, 
from  which  it  is  taken  to  the  compressors  and  pumped 
into  the  cylinders.  Several  cylinders  are  filled  simul- 
taneously from  the  compressors.  When  gas  is  com- 
pressed, heat  is  produced  and  when  a  gas  expands 
cold  is  produced  or  heat  absorbed.  Compressing  the 
oxygen  causes  heat  and  inasmuch  as  a  heated  gas 
occupies  more  space  than  a  cold  gas,  the  cylinder  can- 
not be  filled  with  as  much  oxygen  as  if  this  heating 
did  not  take  place.  This  makes  it  necessary  to  com- 
press the  gas  to  a  greater  degree  than  the  actual  gauge 
pressure  will  show  after  cooling. 

As  a  result  of  the  oxygen  having  come  in  contact 
with  water  in  the  gasometer  or  bad  working  of  the 
compressors,  a  certain  quantity  of  water  vapor  is 
carried  into  the  cylinders  which  will  condense  when  the 
cylinder  cools  and  collect  as  water  in  the  bottom  of 
the  cylinder. 

Volume  of  Oxygen  in  Cylinders. — Oxygen  cylinders 
usually  employed  in  welding  contain  volumes  of  gas 
ranging  from  10  to  200  cubic  feet  when  not  under 
compression.  The  volume  which  a  compressed  gas 
would  occupy  at  atmospheric  pressure  is  found  by 
multiplying  the  capacity  of  the  cylinder  by  the  pres- 


OXYGEN  37 

sure   of  the   gas   expressed  in   atmospheres  of   14.7 
pounds  each. 

An  interesting  problem  is  as  follows :  Assume  that 
a  certain  torch  uses  28  cubic  feet  of  oxygen  per  hour 
and  that  the  welder  is  about  to  start  en  a  job  of  weld- 
iiig  that  will  require  one  hour  to  complete. 

He  has  at  his  disposal  but  one  100  cubic  feet 
cylinder  of  oxygen  under  a  pressure  of  50  atmospheres 
or  735  pounds.  Owing  to  the  fact  that  blowpipes 
usually  consume  more  than  their  rated  capacity,  an 
allowance  should  be  made  for  this,  and  in  this  case 
an  increase  of  about  25  per  cent  over  the  rating  will 
be  allowed,  making  the  actual  volume  of  gas  consumed 
35  cubic  feet  per  hour. 

Suppose  the  internal  capacity  engraved  on  the 
cylinder  is  0.83  cubic  feet.  Since  the  pressure  is  50 
atmospheres,  the  volume  of  oxygen  at  the  disposal  of 
the  welder  is  equal  to  .83  X  50  =  41.5  cubic  feet. 

With  41.5  cubic  feet  of  gas  in  the  cylinder  and  an 
estimated  consumption  of  35  cubic  feet,  also  deducting 
the  2  or  3  cubic  feet  that  will  remain  in  the  cylinder 
wrhen  the  pressure  is  too  low  to  force  the  gas  to  the 
blowpipe,  the  welder  can  safely  undertake  the  work, 
although  it  would  be  advisable  to  work  rapidly  and 
endeavor  to  finish  in  less  than  one  hour. 

It  is,  of  course,  understood  that  such  a  calculation  is 
only  approximate,  but  in  practice  it  can  become  of  real 
value  to  the  welder. 

Boyle's  Law,  which  is,  that  the  volume  of  a  gas 
diminishes  in  the  same  ratio  as  the  pressure  upon  it  is 
increased,  is  only  approximate.  For  oxygen  it  requires 
serious  corrections,  especially  at  certain  pressures. 
The  law  is  only  strictly  true  when  applied  to  so-called 
perfect  gases  (which  are  imaginary),  and  oxygen  is 


38  OXY-ACETYLENE  WELDING  AND  CUTTING 

not  among  these.  The  scientist  Amagat  drew  up 
tables  of  corrections  for  the  gases  mostly  used,  and 
among  others  for  oxygen. 

When  oxygen  is  compressed,  say,  to  120  atmospheres, 
the  cylinder  contains  more  than  120  times  its  volume 
of  gas  reckoned  at  atmospheric  pressure. 

The  Amagat  correction  varies  with  the  pressure,  and 
therefore  to  calculate  accurately  the  quantity  of  oxy- 
gen remaining  in  a  partly  spent  cylinder  it  would  be 
necessary  to  have  a  complete  table  of  corrections  for 
all  pressures.  In  the  case  of  compressed  hydrogen  the 
corrections  to  be  applied  are  opposite  to  those  of  oxy- 
gen ;  that  is,  in  order  to  have  120  times  the  volume  of 
gas  in  the  cylinder  the  hydrogen  must  be  compressed 
to  a  higher  value  than  120  atmospheres. 

We  will  now  deal  with  the  effect  of  temperature, 
because  this  is  an  important  factor. 

It  has  already  been  proved  that  the  volume  of  a  gas 
increases  with  an  increase  of  temperature,  and  that 
this  is  true  for  a  gas  under  pressure,  the  increased 
volume  following  Boyle's  Law.  Consequently,  when 
the  temperature  of  oxygen  in  a  cylinder  is  increased  or 
diminished,  the  pressure  rises  or  falls. 

The  calculations  are  usually  based  on  a  temperature 
of  15°  Cent.  (59°  Fahr.).  This  is  the  temperature  for 
which  Amagat  constructed  his  curves  of  correction  for 
Boyle's  Law.  For  calculating  the  volume  of  the  gas 
stored  in  oxygen  cylinders  the  pressure  must  therefore 
be  taken  at  59°  Fahr.  (15°  Cent.). 

Pressures  and  Temperatures. — An  investigation 
indicated  that  oxygen  compressed  into  a  cylinder  at 
15°  Cent,  and  a  pressure  of  150  atmospheres  is  raised 
to  the  following  pressures  as  its  temperature  is  in- 
creased : — 


OXYGEN  39 

At  20°  Cent 152.8  atmospheres. 

At  25°  Cent 155.6  atmospheres. 

At  30°  Cent 158.4  atmospheres. 

At  35°  Cent 161.4  atmospheres. 

And  if  the  pressure  is  lowered : — 

At    10°  Cent 147.2  atmospheres. 

At      5°  Cent 144.4  atmospheres. 

At      0°  Cent 141.6  atmospheres. 

At  —5°  Cent 138.8  atmospheres. 

These  figures  show  clearly  that  in  calculating  the 
volume  of  oxygen  under  pressure,  temperature  is  an 
important  factor  and  must  be  taken  into  account.  The 
temperature  to  be  taken  is  that  of  the  surrounding  air 
in  which  the  cylinder  has  been  resting  for  several  con- 
secutive hours. 

Another  point  to  be  remembered  is  that,  directly 
after  a  quantity  of  oxygen  has  been  taken  out,  the 
temperature  of  that  remaining  in  the  cylinder  is  con- 
siderably lowered  as  a  result  of  the  expansion.  For 
this  reason  the  gauge  pressure  on  the  reducing  valve 
of  a  cylinder  always  rises  a  little  after  a  large  delivery, 
and  as  the  cylinder  regains  the  normal  temperature  of 
the  surrounding  air,  the  pressure  will  again  rise. 

Therefore,  in  order  to  make  an  accurate  calculation 
of  volume  under  existing  conditions  of  pressure  and 
temperature  it  is  necessary : — 

(1)  To  apply  the  Amagat  corrections. 

(2)  To  express  the  pressure  in  atmospheres. 

(3)  To  correct  for  temperature,  which  should  be  at 
15°  Cent,  or  59°  Fahr. 

Handling  of  Oxygen  Cylinders. — Cylinders  con- 
taining compressed  oxygen  can  be  handled  without 
any  special  precautions.  For  use  they  are  placed 
according  to  their  shape,  either  upright  or  horizontal. 


40  OXY-ACETYLENE  WELDING  AND  CUTTING 

A  very  good  arrangement  consists  in  placing  them  in 
an  inclined  position  on  a  support  10  to  15  inches  high, 
thus  bringing  the  valve  into  a  good  position  for 
handling. 

.  Care  should  be  taken  to  prevent  them  from  falling 
which  is  liable  to  occur  -if  the  floor  is  not  level.  Such 
accidents  do  not  affect  the  cylinder,  but  may  injure 
the  workman  or  damage  the  reducing  valves. 

Cylinder  Valves. — Two  valves  are  used  on  the  oxy- 
gen cylinder.  One  is  mounted  directly  in  the  cylinder 
and  remains  with  it  during  shipment.  It  prevents  loss 
of  the  gas  until  wanted  for  use.  This  is  a  needle 
valve  ending  in  a  squared  portion  or  small  hand  wheel 
on  top  of  the  cylinder.  The  valve  stem  passes  down 
through  a  stuffing  nut  and  box  into  the  oxygen  space. 
The  other  valve  is  known  as  the  reducing  valve,  its 
purpose  being  to  take  the  gas  from  the  cylinder  at  a 
pressure  running  up  to  3000  pounds  per  square  inch 
and  deliver  it  to  the  torch  at  5  to  20  pounds  required 
for  welding.  This  reducing  valve  is  attached  to  the 
cylinder  after  receipt  from  the  oxygen  works,  and  is 
kept  as  part  of  the  welding  installation. 

Practically  the  only  thing  the  workman  has  to  do 
with  the  cylinder  valve  is  to  open  and  close  it  as  the 
gas  is  wanted.  If,  on  the  arrival  of  the  cylinders,  the 
valve  is  very  hard  to  open,  the  welder  should  make 
sure  of  its  working  before  placing  the  reducing  valve 
in  position,  so  that  any  powdered  oxide  or  other  dust 
is  blown  away.  The  oxygen  on  escaping  into  the  air 
produces  a  violent  hissing;  the  valve  is  opened  and 
closed  alternately  two  or  three  times,  and  then  tested 
for  being  gas-tight  when  closed.  The  slightest  escape 
can  usually  be  detected  by  the  ear. 

All  being  well,  it  only  remains  to  screw  on  the  re- 


OXYGEN 


41 


ducing  valve,  and  the  only  important  precaution  is  to 
open  the  cylinder  very  slowly  at  each  starting.  The 
valve  may  be  hard  to  maneuver  or  shift,  either  at  the 
union  for  the  reducing  valve  or  at  the  stuffing-box 
nut  under  the  key  or  handwheel. 

In  no  case  should  oil,  grease,  soap,  or  any  fatty  mat- 
ter be  used.    Oxygen  under  pressure  has  an  oxidizing 


Figure  7. — Section  of  a  Cylinder  Valve 

action  on  oil,  grease  and  fatty  bodies,  and  the  heat  pro- 
duced can  start  combustion;  the  conflagration  may 
spread  to  the  ebonite  part  of  the  valve  and  destroy  the 
steel  parts.  The  oxygen  then  escapes  in  large  quan- 
tities from  the  cylinder,  thus  tending  to  produce  a 
brisk  combustion  by  contact  with  a  lighted  body,  and 
serious  accidents  may  result. 

If,  after  closing  the  valve,  there  is  still  an  escape, 
which  is  shown  by  the  pointer  of  the  gauge  rising 
after  the  valve  of  the  cylinder  has  been  closed,  try  to 


42 


OXY-ACETYLENE  WELDING  AND  CUTTING 


screw    the    valve    tight,    but    without    overdoing    it, 
because  it  becomes  difficult  to  reopen. 

If  the  leak  still  continues,  remove  the  reducing  valve 
and  open  the  valve  briskly  two  or  three  turns  and  then 
immediately  close ;  repeat  this  two  or  three  times.  If 
this  proves  a  failure,  it  only  remains  to  use  the  reduc- 
ing valve  for  obtaining  tightness,  the  regulating  screw 


Figure  8. — Section  of  a  Cylinder  Valve 

being  completely  free  in  such  a  manner  that  the  pres- 
sure does  not  act  on  the  diaphragm. 

Figures  7  and  8  show  sections  of  two  types  of  valves. 

Leaks  sometimes  occur  past  the  nut  of  the  stuffing- 
box  under  the  key  or  handle  (9  in  Figure  7)  ;  this  is 
because  the  packing  (10  in  Figure  7)  is  worn.  This 
can  be  changed  by  screwing  off  the  nut,  but  before  car- 
rying out  this  operation  one  must  make  sure  that  the 
valve  is  entirely  closed,  because,  on  unscrewing,  the 
pressure  can,  with  great  violence,  blow  the  various  de- 
tails out,  and  the  cylinder  be  entirely  emptied. 


OXYGEN  43 

Great  caution  is  recommended  in  dismounting  a 
valve  of  a  cylinder  under  pressure,  and  it  is  better  to 
abstain  entirely  if  one  is  not  perfectly  familiar  with 
the  operation.  In  this  case,  and  when  the  leak  is  con- 
siderable, the  cylinder  should  be  returned  to  the 
makers  with  an  explanatory  label  attached  to  it. 

As  previously  mentioned,  there  is  always  a  small 
quantity  of  water  in  the  cylinder.  Care  should  be 
taken  to  remove  this  and  so  avoid  freezing  in  the 
valve,  especially  in  winter,  when  using  a  blowpipe  of 
large  delivery,  as  the  expansion  produces  considerable 
cooling.  It  is  only  necessary  to  invert  the  cylinder  so 
as  to  collect  the  water  near  the  head,  and  then  expel 
the  liquid  in  jerks  by  successively  opening  the  valve. 
Following  this,  put  back  the  cylinders  on  end  and,  be- 
fore fixing  the  reducing  valve,  operate  for  the  expul- 
sion of  dust  in  the  manner  previously  indicated. 

If  at  any  time  the  valve  should  freeze  and  it  be- 
comes necessary  to  melt  the  ice,  warm  water  should  be 
used.  Never  use  a  flame  as  there  is  danger  in  such 
practice.  However,  if  the  water  has  been  carefully 
expelled  from  the  tank,  there  can  be  no  freezing  of 
valves  under  ordinary  conditions. 

In  order  to  avoid  excessive  expansion  of  the  gas 
and  consequent  increase  in  pressure  the  cylinders 
should  always  be  kept  away  from  a  warm  place,  in 
sunshine,  near  fires,  radiators,  etc. 

After  emptying  the  cylinder  the  valve  should  be 
closed,  the  cap  put  on  and  the  cylinder  returned  to  the 
manufacturers. 

PURITY  OF  OXYGEN 

Oxygen  obtained  from  liquid  air  may  contain 
more  or  less  nitrogen.  That  obtained  by  the  electrol- 


44  OXY-ACETYLENE  WELDING  AND  CUTTING 

ysis  of  water  might  contain  a  little  hydrogen.  These 
two  gases  are  considered  as  impurities.  If  hydrogen 
were  present  to  an  appreciable  extent,  it  would  pro- 
duce the  disadvantage  of  forming  with  the  oxygen  an 
explosive  mixture.  It  has  been  demonstrated  that  in 
the  cutting  of  iron  and  steel  by  blowpipe  cutters  the 
presence  of  nitrogen,  even  in  small  quantities,  has  an 
adverse  effect  on  the  quality  and  rapidity  of  the 
work. 

Commercial  Guarantee. — Oxygen  compressed  in  cyl- 
inders is  generally  delivered  containing  96  to  99  per 
cent  of  oxygen,  -but  the  commercial  guarantee  may  be 
as  low  as  95  per  cent ;  that  is  to  say,  if  analysis  gives 
a  result  lower  than  this  figure,  no  claim  can  be  made 
except  in  case  of  special  agreements.  Oxygen  for  use 
in  cutting  should  be  as  pure  as  possible  and  have  a 
minimum  guarantee  of  97  per  cent. 

Analysis. — The  purity  of  the  gas  is  easily  ascer- 
tained by  acting  on  a  definite  quantity  of  oxygen  with 
a  chemical  which  rapidly  absorbs  the  gas  but  leaves  the 
impurities,  hydrogen,  nitrogen,  carbon  dioxide,  etc., 
intact.  The  quantity  of  gas  absorbed,  compared  with 
the  original  volume,  shows  the  degree  of  purity. 

The  analysis  is  made  in  graduated  test  tubes.  The 
absorbent  liquid  takes  the  place  of  the  oxygen  ab- 
sorbed so  that  when  the  absorbtion  is  complete,  it  is 
only  necessary  to  read  off  the  level  of  the  liquid  to 
find  the  percentage  of  pure  oxygen.  Until  recently 
the  absorbing  liquid  generally  used  was  a  mixture  of 
saturated  solution  of  pyrogallic  acid  and  potash  or 
caustic  soda.  The  preparation  and  use  of  this  liquid 
presented  many  difficulties  to  those  not  accustomed  to 
gas  analysis.  In  addition  to  this  the  alkaline  pyro- 
gallate  solution  has  the  disadvantage  of  absorbing 


OXYGEN  45 

carbon  dioxide  and  of  liberating  bubbles  of  carbonic 
oxide  which  vitiates  the  result.  It  was  formerly  the 
practice  after  analysis  to  add  2  per  cent  to  the  ob- 
served result,  because  it  was  always  about  this  value 
below  the  true  percentage. 

Analysis  by  Sodium  Hydrosulphite. — A  more  prac- 
tical process  than  the  above  has  been  devised,  which 
consists  in  using  a  solution  of  hydrosulphite  of  sodium 
as  the  absorbing  agent.  By  means  of  this  process 
purchasers  of  oxygen  can  easily  test  the  purity  of  the 
gas  they  are  using. 

Sodium  hydrosulphite  is  a  white  salt  which  is  not 
acted  on  by  the  oxygen  in  the  air  when  in  a  dry  state. 
It  must  be  preserved  in  well  stoppered  bottles  in  a 
dry  place. 

A  solution  in  water  has  a  great  affinity  for  ox- 
ygen. The  solution  becomes  a  yellowish  brown  color 
when  absorbing  oxygen.  The  anaylsis  is  performed 
with  the  aid  of  a  tube  having  a  valve  at  each  end, 
called  a  burette.  The  straight  part  of  this  tube  is 
graduated  to  100  cubic  centimeters. 

The  tube  is  connected  to  the  oxygen  cylinder  by  a 
branch  tube,  the  cocks  are  opened  and  the  oxygen  is 
allowed  to  run  through  the  burette  for  20  to  30  sec- 
onds to  expel  all  air.  The  valves  are  then  closed  suc- 
cessively from  the  oxygen  cylinder  toward  the  outlet 
of  the  burette  so  that  the  sample  will  not  be  con- 
fined under  pressure. 

The  burette  is  then  transferred  to  a  vessel  containing 
hydrosulphite  dissolved  in .  water  and  one  end  of  the 
burette  is  dipped  into  this  solution.  The  strength  of 
this  solution  should  be  about  15  per  cent. 

The  valve  on  the  burette  which  is  next  the  solution 
i$  now  opened  so  that  the  oxygen  and  the  solution  come 


46 


OXY-ACETYLENE  WELDING   AND  CUTTING 


together  and  the  oxygen  is  absorbed.  The  absorption 
can  be  hurried  by  carefully  closing  the  valve  in  the 
burette  and  shaking  it,  causing  the  liquid  to  present  a 
larger  surface  to  the  gas.  The  burette  is  again  placed 
in  communication  with  the  solution  and  the  cock 
opened,  and  the  liquid  rises  in  the  tube.  By  repeat- 
ing this  operation  two  or  three  times  the  analysis  is  ex- 


Figure  9. — Analysis  of  Oxygen 

tremely  rapid.  When  the  liquid  ceases  to  rise  any 
more  the  reaction  is  terminated,  and  by  reading  the 
level  of  the  liquid  the  purity  of  the  oxygen  is  knowrn, 
which  may  reach  over  99  per  cent,  that  is,  the  ab- 
sorbing liquid  almost  completely  fills  the  tube. 

A  few  precautions  are  necessary,  especially  in  fill- 
ing the  tubes,  to  make  sure  that  all  air  is  expelled,  and 
to  manipulate  in  such  a  manner  as  to  avoid  introduc- 


OXYGEN  47 

tion  of  air  through  the  cocks,  under  the  effect  of  a 
vacuum,  in  the  inserted  end. 

One  can  facilitate  the  rising  of  the  liquid  at  the 
beginning  by  creating  a  slight  pressure  in  the  vessel 
containing  the  absorbing  liquid.  This  can  be  done 
either  by  pushing  down  the  cork  through  which  the 
end  of  the  burette  passes,  or  by  air  from  an  india 
rubber  bellows  (Figure  9). 

It  is  possible  to  operate  differently;  for  example, 
the  hydrosulphite  solution  could  be  introduced  into 
the  burette  by  means  of  a  funnel  fixed  above  the  up- 
per cock ;  on  opening  the  cock  the  liquid  rapidly  flows 
down,  taking  the  place  of  the  oxygen  which  it  ab- 
sorbs. 


CHAPTER  IV 

ACETYLENE 

Acetylene  was  discovered  in  1836  by  Humphrey 
Davy,  an  English  chemist,  and  Berzelius,  a  Swiss  chem- 
ist. They  found  that  the  residue  which  had  been  ob- 
tained incidentally  in  the  production  of  metallic  potas- 
sium was  capable  of  decomposing  water  with  the  evolu- 
tion of  a  gas  which  contained  acetylene.  It  is  also 
produced  during  the  incomplete  combustion  of  cer- 
tain gases.  Thus,  when  a  Bunsen  burner  lights  at  the 
bottom  of  the  tube,  acetylene  is  produced.  But  until 
the  industrial  manufacture  of  calcium  carbide  it  re- 
mained a  laboratory  gas. 

Chemically,  acetylene  consists  of  carbon  and  hydro- 
gen, and  is  represented  by  the  formula  C2H2,  meaning 
that  it  has  the  constant  composition  of  24  parts  by 
weight  of  carbon  and  2  of  hydrogen,  or  92.3 
per  cent  of  carbon  and  7.7  per  cent  of  hy- 
drogen. Of  all  the  hydrocarbons  it  is  the  rich- 
est in  carbon.  Acetylene  is  a  colorless  gas,  which, 
when  pure,  has  an  odor  which  is  not  unpleasant.  The 
penetrating  and  disagreeable  odor  is  due  to  impuri- 
ties, notably  phosphoretted  hydrogen,  hydrogen  sul- 
phide, and  the  polymers  of  the  gas ;  these  latter  result 
from  the  heat  generated  in  certain  generators. 

Acetylene  is  lighter  than  air  in  the  proportion  91  to 
100;  its  specific  gravity  or  density  is  therefore  said 
to  be  0.91.  One  cubic  foot  of  the  gas  weighs  0.074 
Ib.  One  Ib.  of  the  gas  occupies,  under  standard  tem- 
perature and  pressure,  13.65  cubic  feet. 

Acetylene  is  soluble  in  a  large  number  of  liquids. 

48 


ACETYLENE  49 

Under  ordinary  temperature  and  pressure,  water  dis- 
solves little  more  than  its  .own  volume,  essence  of  tur- 
pentine and  petrol  2  volumes,  benzene  4,  pure  alcohol 
6,  and  acetone  25.  The  solubility  increases  with  the 
pressure.  Acetylene  is  scarcely  soluble  in  water  sat- 
urated with  marine  salt. 

When  heated  to  a  temperature  of  about  600°  Cent. 
(1112°  Fahr.)  acetylene  polymerizes  into  a  number  of 
products  more  or  less  related  to  benzene.  The  forma- 
tion of  benzene  by  polymerization  takes  place  with  dis- 
engagement of  heat  (178  calories  or  44  B.T.U.). 

Acetylene  under  atmospheric  pressure  becomes  a 
liquid  at  — 82°  Cent.  (—115°  Fahr.)  and  a  solid  at 
-85°  Cent.  (—121°  Fahr.). 

Acetylene  under  no  pressure  or  under  a  slight  pres- 
sure is  not  explosive,  but  this  is  not  the  case  when 
compressed. 

Berthelot  showed  that  acetylene,  subjected  to  a  pres- 
sure of  l1/^  atmospheres,  can  decompose  into  its  ele- 
ments under  the  influence  of  a  shock,  slight  heating, 
or  any  percussion  whatever.  Such  decomposition 
produces  a  violent  explosion. 

In  practice  the  maximum  should  be  much  lower  than 
this,  and  acetylene  should  never  be  kept  under  a  pres- 
sure of  more  than  a  few  pounds.  On  the  other  hand, 
acetylene  absorbed  under  pressure  by  liquids  which 
dissolve  it,  such  as  acetone,  is  absolutely  safe. 

Acetylene  is  an  endothermic  body,  that  is,  it  is 
formed  with  the  absorption  of  heat.  This  heat  is  then 
given  up  at  the  time  of  combustion  contributing  pow- 
erfully to  the  rise  in  temperature  in  the  flame.  Mix- 
tures of  acetylene  and  air,  and,  of  course,  of  acetylene 
and  oxygen,  explode  violently  when  ignited.  The 
temperature  of  ignition  being  very  low,  a  spark  is  suffi- 


50  OXY-ACETYLENE  WELDING  AND  CUTTING 

cient  to  set  fire  to  the  mixture.  The  formation  of  such 
mixtures  should  be  avoided,  and  most  certainly  their 
ignition.  The  propagation  of  the  flame  can  take  place 
through  extremely  small  holes.  The  explosion  of  a 
vessel  of  one  quart  capacity  containing  a  mixture  of 
acetylene  and  oxygen  is  violent  enough  to  cause  the 
death  of  a  person  near  it.  It  is  very  easy  to  avoid 
the  formation  of  such  mixtures  as  will  be  seen  later. 

Carbide  of  Calcium. — The  discovery  of  the  process 
of  the  manufacture  of  carbide  of  calcium  is  due  to 
the  work  of  a  French  chemist,  Moissan,  and  an  Amer- 
ican electro-metallurgist,  Wilson. 

Carbide  of  calcium  consists  of  calcium  and  carbon 
and  is  represented  by  the  formula  CaC2.  It  consists 
of  62.5  per  cent  of  calcium  and  37.5  per  cent  of  car- 
bon. The  color  varies  from  earthy  gray  to  luminous 
black,  sometimes  possessing  a  range  of  colors  similar  to 
tempered  steel.  The  texture  is  usually  massive  and 
crystalline,  although  in  some  cases  spongy.  Neither 
the  color  nor  the  texture  serves  to  indicate  the  good 
or  bad  qualities  of  the  carbide. 

Carbide  of  calcium  has  the  hardness  of  stone.     Its 
specific  gravity  ranges  from  2.2  to  2.3.  It  is  noninflam- 
mable  and  it  softens  and  melts  at  about  5400°  Fahr. 
In  the  presence  of  water  vapor  or  water  it  decom- 
poses into  acetylene  gas  and  oxide  of  calcium  (lime)  : 
CaC2  +  H,0  =  CaO  +  C2H2 
64  +  18     ==     56  +  26 

According  to  this  equation,  64  parts  by  weight  of 
carbide  requires  18  parts  by  weight  of  water,  or  1 
pound  of  carbide  requires  0.225  pints  of  water.  These 
are  purely  theoretical  quatities  and  do(  not  take  into 
account  the  evaporation  of  the  water  and  the  absorp- 
tion of  the  water  by  the  lime  which  forms  quick  lime. 


ACETYLENE  51 

In  practice  it  is  necessary  to  use  1.2  to  1.6  pints 
of  water  for  each  pound  of  carbide  in  those  generators 
known  as  water  to  carbide  and  dripping ;  and  5  to  5.5 
pints  of  water  to  each  pound  of  carbide  in  carbide  to 
water  types  of  generator.  These  quantities  insure  that 
the  lime  residue  may  be  removed  in  liquid  form. 

Theoretically,  one  pound  of  carbide  yields  5.5  cubic 
feet  of  acetylene  at  standard  temperatures  and  pres- 
sure. The  action  is  always  accompanied  by  a  rapid 
liberation  of  heat ;  226  calories  or  900  B .  T .  U.  for  each 
pound  of  carbide. 

Manufacture  of  Carbide. — Carbide  of  calcium  is 
made  by  fusing  a  mixture  of  lime  and  carbon  (coke 
or  anthracite),  in  the  proportion  of  56  parts  by  weight 
of  lime  to  36  parts  by  weight  of  carbon,  in  an  elec- 
tric furnace,  the  temperature  of  which  is  about  7200° 
Fahr.  The  carbon  should  not  contain  more  than  5  per 
cent  of  ash  and  the  lime  should  be  as  free  as  possible 
from  phosphates.  The  economical  production  of  car- 
bide depends  to  a  great  extent  on  the  low  price  of 
electrical  energy.  Manufacturers  of  carbide  cannot 
establish  themselves  unless  a  minimum  power  of  from 
2000  to  3000  horse  power  can  be  utilized. 

Under  the  enormous  temperature  of  the  electric 
furnace,  the  lime  and  carbon  combine  and  the  liquid 
carbide  which  results  flows  easily,  then  cools  and 
solidifies  in  large  blocks.  As  soon  as  they  are  suffi- 
ciently cool,  the  blocks  of  carbide  are  conveyed  to 
the  crushing  and  granulating  room  where  the  carbide 
passes  through  crushers.  The  pieces  are  then  sorted 
with  sieves  and  graded  according  to  size.  Part  of  the 
crushed  carbide  is  carried  to  the  granulating  appara- 
tus which  separates  it  into  pieces  of  regular  small 
size.  The  dust  is  removed  and  the  graded  carbide 


52  OXY-ACETYLENE  WELDING  AND  CUTTING 

is  packed  in  drums,  the  covers  of  which  are  tightly 
sealed. 

Classification. — The  sizes  packed  in  drums  are  de- 
signated as  follows: 

(1)  Lump,  a  large  size  (3%  in.  X  2  in.),  con- 

taining nothing  smaller  than  two  inch 
pieces. 

(2)  Egg,  a  medium  size   (2  in.  X  %  in.),  con- 

taining  nothing  smaller  than  one-half  inch 
pieces. 

(3)  Nut,  an  intermediate  size  (1^  in.  X  %  in.)> 

for  use  in  carbide  to  water  machines  using 
larger  than  quarter  and  smaller  than  egg. 
Machines  especially  made  to  use  quarter 
size  cannot  use  nut  size. 

(4)  Quarter,  a  finely  crushed  size  (14  in-  X  yV 

in.),  all  small  pieces  and  adapted  for  use 
in  generators  in  which  finely  crushed  car- 
bide is  fed  into  water. 

Analysis  of  Carbide. — The  exact  gas  yield  of  car- 
bide of  calcium  cannot  be  measured  by  the  volume 
calculated  from  the  meter  reading,  nor  by  the  deliv- 
ery at  the  blowpipe,  nor  by  the  length  of  time  taken 
to  exhaust  a  certain  quantity  of  carbide.  These  in- 
dications are  of  some  use  for  comparison  of  different 
samples  of  carbide,  provided  the  gas  is  always  liber- 
ated under  identical  conditions.  They  give  an  ap- 
proximate idea  of  the  respective  qualities,  but  are 
always  liable  to  errors. 

The  accurate  analysis  always  necessitates  the  em- 
ployment of  a  special  apparatus,  which  will  indicate 
accurately  the  amount  of  gas  liberated  by  a  sample. 
Figure  10  shows  the  apparatus  used  for  the  accurate 
analysis  of  carbide. 


ACETYLENE 


53 


ACETYLENE  GENERATORS 


General  Principles  of  Production. — The  production 
of  acetylene  by  the  action  of   water  on  carbide  of 


Figure  10. — Apparatus  for  Analysis  of  Carbide 

calcium  is  chemically  one  of  the  simplest  reactions, 
but  in  practice  it  is  not  so  simple.     The  two  prin- 


54  OXY-ACETYLENE  WELDING  AND  CUTTING 

cipal  difficulties  connected  with  the  process  are  heat- 
ing and  over  production. 

Heating. — This  is  due  to  two  causes.  In  the  first 
place,  since  water  consists  of  hydrogen  and  oxygen,  the 
dissociation  of  these  two  gases  takes  place  with  the  ab- 
sorption of  heat.  On  the  other  hand,  the  oxygen  that 
is  liberated  combines  with  the  calcium  carbide  and 
produces  by  the  reaction  more  heat  than  is  absorbed 
by  the  first  reaction.  The  heat  liberated  exceeds  226 
calories,  or  900  B .  T .  U.  per  pound  of  carbide ;  that  is, 
one  pound  of  carbide  would  raise  the  temperature  of 
one  gallon  of  water  through  90°  Fahr.  No  device  nor 
arrangement  can  reduce  the  quantity  of  heat  liberated, 
but  the  temperature  of  the  mass  may  be  controlled. 
For  instance,  if  an  excess  of  cold  water  is  used,  the 
boiling  temperature  of  the  water  cannot  be  reached, 
but,  if  the  carbide  is  in  excess  in  proportion  to  the 
water,  the  temperature  can  reach  higher  values.  This 
causes  the  water  to  vaporize  and  react  with  the  mass 
of  carbide,  thus  supplementing  the  heat  and  under 
the  influence  of  heat  the  lime  can  give  up  its  water, 
which  it  retains  strongly  at  low  temperatures,  to  the 
carbide.  These  reactions  continue,  and  if  there  is 
no  external  cooling,  the  temperature  continues  to  rise. 
Lime  being  a  bad  conductor  of  heat,  the  mixture  call 
become  red  hot. 

The  disadvantages  resulting  from  the  generation  of 
acetylene  at  a  high  temperature  are  of  two  kinds — 
polymerization  and  great  impurity. 

Polymerization.— Under  the  influence  of  heat,  acet- 
ylene polymerizes  or  condenses  into  liquid  or  solid 
products.  This  action  takes  place  more  readily  during 
the  formation  of  the  acetylene  than  after  generation. 
Numerous  experiments  have  shown  that  these  poly- 


ACETYLENE  55 

mers  are  formed  in  acetylene  generators  at  a  temper- 
ature of  266°  Fahr.  These  tarry  substances  become 
fastened  on  the  lime  and  discolor  it  yellow.  Being 
formed  from  the  acetylene  they  correspond  to  a  loss 
of  gas. 

Impurity. — This  is  a  serious  disadvantage.  Car- 
bide, when  acted  upon  by  heat,  gives  up  sulphides. 
Water  decomposes  these  into  hydrogen  sulphide  and 
organic  sulphur  compounds  which  are  detrimental  to 
acetylene.  The  higher  the  temperature  of  produc- 
tion the  more  impure  the  gas.  Heating  imparts  to  the 
gas  the  unpleasant  odors  of  the  sulphur  polymers. 

Excess  Production  or  "After  Generation." — No 
acetylene  apparatus  produces  the  gas  in  the  propor- 
tion to  which  it  is  consumed.  The  production  there- 
fore has  necessarily  to  be  either  in  excess  or  in  de- 
ficiency. The  production  should  be  in  advance,  and  a 
sudden  stoppage  of  consumption  cannot  possibly  cor- 
respond to  the  abrupt  arrest  of  the  reaction. 

The  reaction  continues,  and  this  phenomena  has  re- 
ceived the  name  of  excess  production  or  ' '  after  genera- 
tion." In  dipping  and  water  to  carbide  apparatus, 
it  is  necessary  to  take  in  to  account  the  fact  that  the 
slaked  lime  which  covers  the  carbide  at  the  moment 
when  the  water  ceases  to  be  in  contact,  gives  slowly 
to  the  carbide  the  water  it  requires,  which  brings 
about  the  liberation  of  acetylene,  right  up  to  dryness. 

It  is  evident  that  for  any  particular  generator,  heat- 
ing and  after  generation  are  in  direct  relation  to  the 
delivery.  It  is  therefore  impossible  to  formulate  rules 
on  these  points  without  taking  into  account  the  de- 
livery. 

With  reference  to  the  maximum  delivery  of  any 
particular  apparatus : — 


56  OXY-ACETYLENE  WELDING  AND  CUTTING 

(1)  The  heating  should  never  exceed  a  tempera- 
ture of  130°  Cent.  (266°  Fahr.). 

(2)  It  should  be  possible  to  accumulate  and  use  the 
after  generation  in  case  of  stoppage. 

Classification. — Acetylene  apparatus  can  be  divided 
into  two  classes : — 

(1)  Apparatus  for  intermittent  production,  called 
also  non-automatic,  in  which  the  quantity  of  gas  is 
prepared  beforehand,  and  kept  in  a  gasometer  of  a  size 
suitable  for  the  maximum  consumption  for  one  or 
several  days.     Such  apparatus  is  constructed  on  the 
principal  of  the  fall  or  immersion  of  a  fixed  quantity 
of  carbide  into  a  mass  of  water. 

(2)  Automatic  apparatus,   in  which  acetylene  is 
produced  in  proportion  to  the  consumption,  such  ap- 
paratus being  mostly  employed.  Automatic  apparatus 
can  be  divided  into  three  main  classes,  viz.,  water  to 
carbide,  dipping  or  contact,  and  carbide  to  water. 

The  water  to  carbide  apparatus  is  on  the  principle 
of  a  gasometer  with  a  movable  bell,  or  on  the  principle 
of  the  flowing  back  of  water  from  the  gasometer.  The 
automatic  function  is  brought  about  in  the  first  case 
by  the  movement  of  the  movable  bell,  and  in  the  sec- 
ond case  by  the  change  in  pressure. 

In  the  dipping  or  contact  generators,  the  carbide  can 
be  fixed  and  the  water  moving,  or  the  water  fixed 
and  the  carbide  moving. 

In  the  carbide  to  water  generators  carbide  of  all 
sizes,  broken  or  granulated,  is  used.  The  carbide  is 
usually  automatically  regulated  by  the  movement  of 
the  movable  bell. 

Comparison  of  Systems. — Every  system  for  the  pro- 
duction of  acetylene  has  its  advantages  and  disad- 
vantages. Before  attempting  to  describe  these  it 


ACETYLENE 


57 


should  be  noted  that  these  advantages  and  disadvan- 
tages come  more  or  less  into  consideration  accord- 
ing to  the  construction  of  the  apparatus  and  the  use 
to  which  it  is  to  be  put.  In  other  words,  any  par- 
ticular advantage  or  disadantage  may  be  increased  or 
decreased  according  to  the  particular  use  for  which  a 
given  acetylene  plant  is  designed. 

Water  to  Carbide. — Figure  11  is  a  sectional  eleva- 
tion of  one  apparatus,  showing  the  principles.     Com- 


Figure  11. — Section  of  Automatic  Water  to  Carbide  Generator 

pared  to  carbide  to  water  generators,  it  has  the  disad- 
vantage of  necessitating  longer  and  less  convenient 
cleaning,  producing  less  pure  gas  and  of  losing  gas, 
especially  in  the  case  of  sudden  stoppage  with  a  gas- 
ometer of  too  small  size. 

Figure  12  shows  a  complete  generator  of  this  type. 
An  advantage  in  favor  of  this  system  is  that  the  gener- 
ator consumes  less  water,  is  simple  in  its  working,  ab- 
solutely safe  and  produces  an  excellent  quantity  of 
gas,  especially  if  the  after  generation  is  well  stored. 


58 


OXY-ACETYLENE  WELDING  AND  CUTTING 


Dipping. — These  generators,  illustrated  in  Figures 
13  and  14,  cause  the  greatest  amount  of  heat  and 


Figure  12. — One  Type  of  Automatic  Water  to  Carbide  Generator 

after  generation  and  produce  the  most  impure  gas. 
However,  their  great  simplicity  renders  their  use  ad- 
vantageous for  small  portable  plants  having  small  de- 


Figure  13. — Section  of  Automatic  Dipping  Generator 

livery  and  which  have  to  continue  generation  until 
the  whole  of  the  carbide  is  used  up.  This  method 
should  be  rejected  for  large  generators. 


ACETYLENE 


59 


Carbide  to  Water. — Figures  15  to  19  illustrate  the 
various  types  of  generators  used  in  this  process.    Its 


Figure   14. — One   Type   of  Automatic   Dipping   Generator 

advantages  and  disadvantages  may  be  enumerated  as 
follows:  The  gas  is  cool,  free  from  ammonia  and  hy- 
drogen sulphide,  and  greater  variation  in  delivery  may 


Figure   15. — Section   of  Automatic   Carbide   to  Water   Generator 

be  obtained.  These  generators  may  be  easily  cleaned 
and  automatically  emptied.  Its  disadvantages  include 
the  greater  size  for  an  equal  yield  of  gas,  greater 


60 


OXY-ACETYLENE  WELDING  AND  CUTTING 


consumption  of  water  and  a  great  amount  of  liquid 
residue. 

Granulated  Carbide  to  Water. — The  disadvantages 


Figure  16. — Automatic  Carbide  to  Water  Generator 


Figure  17. — Section  of  Granulated  Carbide  to  Water  Generator 

of  this  type,  as  compared  with  the  last  one  considered, 
include  a  smaller  yield  of  gas  and  greater  cost  of  car- 
bide. All  generators  of  this  type  in  which  the  carbide  is 
distributed  by  a  conical  valve  or  a  flat  valve  (see  Fig- 


ACETYLENE 


(II 


ure  17)  are  dangerous  if  the  carbide  capacity  exceeds 
2  to  5  pounds  or  where  not  working  in  the  open  air. 
It  is  possible,  as  a  result  of  faulty  working,  for  a  piece 


Figure  18. — Granulated   Carbide  to  Water  Generator 

A 


Figure  19. — Distribution  of  Granulated  Carbide  by  Bucket  Wheel 


of  carbide  that  is  too  large,  or  a  foreign  body  to 
cause  the  entire  charge  to  fall  into  the  water  at  once. 
On  the  other  hand,  such  an  occurrence  cannot  take 


62 


OXY-ACETYLENE  WELDING   AND  CUTTING 


Figure   20. — Automatic    Acetylene    Generator 

place  if  the  granulated  carbide  is  distributed  by  a 
bucket  wheel  (Figure  19)  in  which  the  distribution  is 
definitely  divided.  The  advantages  of  these  generators 


ACETYLENE 


63 


are  in  ease  of  charging  and  great  variation  in  deliv- 
ery rate.  They  are  also  less  bulky  and  require  smaller 
gasometers.  The  fall  of  the  carbide  may  be  quite  fre- 
quent owing  to  the  rapid  decomposition  of  the  pieces. 
Automatic. — Figure  20  is  a  semi-sectional  view  of 
a  generator,  showing  the  working  parts  in  detail,  in 
which  lump  carbide  is  used.  The  carbide  feed  is  by 
water  motor  which  automatically  maintains  an  even 
pressure  of  gas.  It  is  equipped  with  a  flash  back  pre- 


Figure   21. — Non -automatic   Acetylene   Generator 

venter  and  a  safety  blow-off  valve.  Each  time  the  gen- 
erator is  charged  this  blow-off  valve  is  opened,  which 
insures  its  always  being  in  working  order. 

Non- Automat ic. — Figure  21  is  a  sectional  elevation 
of  this  type.  It  will  be  noticed  that  the  general  prin- 
ciples outlined  in  Figures  11  and  15  control  the  con- 
struction of  this  generator  also.  Non-automatic  gen- 
erators are  used  where  gas  is  made  in  large  quantities 


64  OXY-ACETYLENE  WELDING  AND  CUTTING 

in  advance,  being  stored  in  gasometers  for  future  use. 
While  this  system  is  very  practical,  it  requires  large 
space  and  is  not  well  adapted  for  portable  use. 

Working  Guarantees. — Certain  guarantees  for  good 
working  are  necessary  for  all  types  of  acetylene  gen- 


Fignre  22. — Generator  for  Using1  the  Carbide  in  Compressed 
Cakes 

erators.  For  instance,  each  generator  is  rated  for  a 
given  capacity,  its  normal  charge  of  carbide  being 
a  certain  number  of  pounds  and  its  maximum  output 
being  a  given  number  of  cubic  feet  of  gas  per  hour. 
The  requirements  then  should  be  as  follows : — 

(1)  For  the  rate  of  production  the  temperature 
of  the  carbide  during  decomposition  should  not  reach 
the  point  at  which  acetylene  undergoes  polymeri- 


ACETYLENE  65 

zation,  that  is,  there  should  be  no  tarry  matters,  ben- 
zene, nor  any  deposition  of  yellow  material  on  the 
lime  residue,  when  carbide  of  standard  quality  is 
used. 

(2)  The  capacity  of  the  gasometer  should  be  suffi- 
cient to  contain  the  acetylene  given  off  after  the  water 
supply  has  been  cut  off,  and  there  must  be  no  excess 
of  gas  which  will  be  blown  to  waste  in  the  course  of 
working. 

(3)  The  pipes  and  cocks  between  the  separate  parts 
of  the  plant  should  be  of  such  size  that  there  can  be 
no  considerable  variation  in  pressure,  except  in  cases 
where  variation  of  pressure  is  a  function  of  the  gen- 
erating apparatus,  even  in  case  of  maximum  delivery. 

(4)  The  pressure  of  the  gas  measured  at  the  exit 
of  the  generator  should  be  at  least  equal  to  5  inches 
of  water  (if  possible  obtain  6). 

(5)  This  pressure  should  be  practically  constant, 
the  variation  not   exceeding  half  an  inch  in  either 
direction,  at  any  time  during  the  working  of  the  gen- 
erator. 

(6)  The  generator  should  be  charged  or  emptied 
without  any  appreciable  loss  of  gas.     The  quantity 
of  air  introduced  in  emptying  and  charging  the  gen- 
erator should  be  so  small  that  on  mixing  with  the 
smallest  quantity  of  acetylene  which  the  gasometer 
can  contain,  it  shall  have  no  bad  effect  on  the  work- 
ing of  the  blowpipe. 

(7)  Subject  to  ordinary  wear  and  tear  and  pro- 
vided the  generator  is  used  according  to  the  manufac- 
turer's rules  and  instructions,  its  good  working  should 
be  guaranteed  for  a  period  of  years. 

Special    Generators. — There    have    been    made   for 
welding  purposes  special  acetylene  generators  which 


66  OXY -ACETYLENE  WELDING  AND   CUTTING 

give  certain  results  which  are  of  more  or  less  import- 
ance. The  special  characteristic  is  the  obtaining  of  an 
increase  of  pressure,  which  makes  it  possible  to  use 
blowpipes  for  medium  pressure  acetylene.  Among 
other  advantages  obtained  with  these  transportable 
generators  is  the  absence  of  excess  production,  regu- 
larity of  working  and  facility  of  employment,  which 
makes  them  recommendable  in  practice.  One  type  of 
this  generator  made  for  fixed  installations  is  on  the 
" flowing  back  of  water  from  the  gasometer"  prin- 
ciple, and  is  capable  of  supplying  acetylene  at  from 
60  to  100  inches  of  water  pressure. 


CHAPTER  V 

PURIFICATION  OF  ACETYLENE 

Impurities  in  Carbide  and  Acetylene. — Industrial 
carbide  of  calcium  is  not,  and  cannot  be,  a  pure  prod- 
uct. The  chief  constituents  are,  as  we  know,  lime  and 
carbon  (metallurgical  coke  or  anthracite),  and  no  mat- 
ter what  care  is  taken  will  contain  impurities.  Com- 
pounds of  sulphur  are  to  be  found  in  the  best  coke  or 
coal,  and  phosphates  in  the  purest  lime.  These  impur- 
ities combine  with  calcium  in  the  electric  furnace,  and, 
like  carbide,  the  products  formed  are  decomposed  by 
water  or  heat,  so  that  acetylene  always  contains,  more 
or  less,  phosphoretted  hydrogen  and  hydrogen  sul- 
phide, the  amount  depending  on  the  generator  used. 

In  addition  to  these  two  gases  there  should  be  in- 
cluded a  little  ammonia  produced  by  the  decomposi- 
tion, by  means  of  the  water  in  contact  with  the  lime,  of 
the  nitrodes  and  cyanamide  which  the  carbide  con- 
tains, due  to  combination  with  the  nitrogen  of  the  air 
at  the  moment  of  cooling. 

To  these  chemical  impurities  it  is  necessary  to  add 
the  solid  matters  in  a  fine  state  of  division  which  are 
suspended  in  the  gas  and  which  have  been  given  off  by 
the  lime  at  the  moment  of  decomposition. 

The  phosphoretted  hydrogen  is  always  carried  along 
with  the  acetylene ;  the  hydrogen  sulphide,  ammonia, 
and  the  fine  dust  from  the  lime  can  be  retained  by  the 
generator  according  to  the  system,  but  they  generally 
go,  more  or  less,  with  the  acetylene. 

Necessity  for  Purification  in  Welding  with  Oxy- 
Acetylene. — The  impurities  in  the  acetylene,  even  in 

67 


68  OXY-ACE^YLENE  WELDING  AND  CUTTING 

very  small  quantities,  can  do  considerable  harm  to  the 
strength  of  the  welds. 

Metallurgists  endeavor  to  remove  phosphorus  and 
sulphur  from  their  iron  and  steel,  because  these  bodies 
alter  considerably  the  mechanical  qualities  of  the 
metal. 

Now,  strange  coincidence,  we  find  them  exactly  in 
that  state  as  impurities  in  acetylene  destined  to  melt 
the  metal  for  obtaining  welds,  that  is  to  say,  ready 
to  incorporate  themselves  in  the  welding  zone,  which 
should  be  particularly  clean  in  order  that  the  weld 
should  be  perfect. 

Phosphoretted  hydrogen  and  hydrogen  sulphide  by 
combustion  produce  phosphoric  acid  and  sulphuric 
acid,  and  these  are  able  to  give  up  their  phosphorus 
and  sulphur  to  the  metal  being  melted.  It  is  true 
that  the  incorporation  is  not  complete,  but  minute 
as  it  is,  the  weld  is  damaged — that  is  incontestable. 

As  far  as  other  metals  than  iron  and  its  alloys  are 
concerned,  this  disadvantage  does  not  exist,  and  in 
the  case  of  copper,  for  example,  the  presence  of  phos- 
phorus cannot  be  anything  but  favorable — but  this 
is  an  exception. 

The  bad  effects  of  the  presence  of  phosphoretted  hy- 
drogen and  hydrogen  sulphide  have  been  frequently 
proved,  especially  in  the  case  where  dissolved  acety- 
lene and  acetylene  from  a  generator  have  been  em- 
ployed successively.  For  example,  in  the  manufac- 
ture of  vessels  destined  to  receive  liquids  or  gases 
under  pressure,  cracks  have  been  frequent  when  using 
non-purified  gas  from  a  generator,  and  infrequent 
in  the  case  of  dissolved  acetylene,  which  is  practically 
pure  acetylene.  It  is  in  such  cases  that  the  superior- 
ity of  purified  gas  has  been  realized. 


PURIFICATION  OF  ACETYLENE  6£ 

It  remains  for  us  to  examine  the  bad  effects  of  the 
fine  dust  that  is  carried  along  with  the  gas,  and  which 
is  so  finely  divided  that  it  does  not  settle  down  with 
long  standing  in  the  gasometer  nor  by  energetic  wash- 
ing. It  is  unnecessary  to  show  the  disastrous  in- 
fluence of  these  particles  of  lime  when  incorporated 
in  the  weld,  and  how  the  wreld  has  been  weakened; 
their  elimination  is  absolutely  necessary.  A  further 
disadvantage  is  that  they  obstruct  the  passage  of  the 
gas  through  the  blowpipe  and  form  a  crust  in  the 
nozzle. 

It  is  obvious,  therefore,  that  the  employment  of  gas. 
which  has  not  been  purified  presents  many  faults ;  the 
statement  of  which  has  not  been  exaggerated,  and 
these  disadvantages  always  exist  in  gas  which  has  not 
been  purified. 

The  oxy-acetylene  flame  in  the  case  of  impure  gas 
is  colored,  and  more  difficult  to  regulate.  Lastly,  the 
anhydrides  of  phosphorus  and  sulphur  produced  by 
the  combustion  of  impure  acetylene  spread  in  the 
atmosphere  and  have  a  dangerous  physiological  effect 
on  the  welders. 

Process  of  Purification. — Washing  of  the  gas  only 
constitutes  a  slight  purification  and  does  not  dissolve 
the  phosphoretted  hydrogen  at  all,  and  only  partially 
the  other  impurities.  Filtration  through  wadding, 
sand,  or  felt,  etc.,  does  not  abstract  the  fine  dust,  and 
the  passage  of  the  acetylene  through  solid  wood  char- 
coal, coke,  sawdust,  etc.,  only  constitutes,  in  general, 
an  imperfect  filtration. 

The  only  practical  way  is  to  fix  the  impurities  by 
chemical  combination. 

The  question  of  purification  has  for  a  long  time 
occupied  numerous  chemists,  the  manufacturers  of 


70  OXY-ACETYLENE  WELDING  AND  CUTTING 

carbide  and  acetylene  generators.  It  is  extremely 
complicated,  and  presents  difficulties  of  many  kinds 
which  it  is  not  necessary  to  dwell  on  here. 

Liquid  purifiers  have  had  to  be  abandoned  com- 
pletely, and  solids  have  been  made  possessing  the  nec- 
essary chemical  properties  to  fix  the  impurities  and 
allow  the  acetylene  to  pass  through  without  being  at- 
tacked. 

Purifying  Materials. — Products  containing  alkali 
hypochlorites  and  alkaline  earths  which  are  able  to  re- 
tain by  chemical  combination  phosphoretted  hydrogen 
have  been  abandoned  because  they  do  not  constitute 
a  perfect  purifier  and  produce  other  serious  difficul- 
ties. The  gas  is  not  filtered  and  carries  along  free 
chlorine  and  lime  dust,  which  are  bad  for  welding, 
and  which  increase  as  the  passage  of  the  gas  through 
the  purifier  is  increased,  following  the  use  of  a  larger 
blowpipe.  Heratol  is  one  purifier  much  used.  It  is 
a  powdered  product  of  which  the  base  is  chromic  acid. 

Second,  the  purification  with  Heratol  is  too  costly, 
and  in  addition  to  this,  the  use  of  Heratol  for  auto- 
genous welding  necessitates  purifiers  with  a  large  sur- 
face. The  passage  of  the  gas  through  the  purifier 
must  not  exceed  0.23  cubic  feet  of  gas  per  hour  per 
square  inch  of  purifying  surface.  If  this  rate  is  ex- 
ceeded, bad  purification  and  heating  of  the  mass  takes 
place,  bringing  about  decomposition  of  the  acetylene. 
Thus  for  a  delivery  of  70  cubic  feet  per  hour  the 
Heratol  purifier  must  have  a  minimum  diameter  of 
20  inches.  Although  these  conditions  are  not  en- 
couraging, the  use  of  such  a  purifier  is  recommended, 
and  those  who  have  used  it  seem  to  be  well  pleased 
with  the  results. 

Catalysol. — This  is  a  purifying  material  which  seems 


PURIFICATION  OF  ACETYLENE  71 

to  meet  most  of  the  requirements  of  autogenous  weld- 
ing. It  is  similar  to  Heratol  in  being  a  yellow  powder 
with  a  specific  gravity  of  0.6  to  0.7.  It  consists  of 
iron  oxy-chlorides  which  act  catalytically  in  such  a 
way  that  the  impurities  of  acetylene  are  completely 
oxidized  by  contact  and  the  acetylene  leaves  the  puri- 
fier in  a  pure  and  unattacked  state. 

The  purifying  power  of  catalysol  is  slightly  supe- 
rior to  Heratol,  but  its  principal  advantage  is  its  power 
of  regeneration  by  simple  exposure  to  the  air,  this  be- 
ing repeated  three  or  four  times  until  the  product  be- 
comes inactive  owing  to  the  absorption  of  the  im- 
purities which  it  has  extracted  from  the  acetylene 
during  its  continued  use. 

Counting  the  first  purifying  with  catalysol  and 
three  regenerations  making  four  purifications  in  all, 
and,  as  each  2%  pounds  of  catalysol  will  handle  100 
pounds  of  carbide;  then  one  pound  of  catalysol  will 
purify  160  pounds  of  average  carbide,  or  about  770 
cubic  feet  of  gas,  as  compared  to  160  to  200  cubic 
feet  in  the  case  of  Heratol. 

The  process  of  regeneration  of  catalysol  is  very 
simple,  it  being  only  necessary  to  take  the  used  ma- 
terial and  replace  it  in  its  original  box  and  after  a 
few  days  it  is  again  ready  for  use.  The  regenera- 
tion may  be  made  more  rapid  by  exposing  it  to  the  air 
in  thin  layers,  care  being  taken  that  it  does  not  become 
moist. 

A  special  quality  is  prepared  for  autogenous  weld- 
ing installations  which  goes  under  the  name  of  weld- 
ing catalysol  or  catalysol  S. 

The  velocity  of  the  gas  through  the  purifier  can 
attain  0.7  cubic  foot  per  hour  for  each  square  inch  of 
surface.  Taking  an  average  of  0.5  cubic  foot,  the 


72  OXY-ACETYLENE  WELDING  AND  CUTTING 

capacity  of  the  purifier  can  be  diminished  to  half 
that  required  in  the  case  of  Heratol,  and  whatever  be 
the  velocity  of  passage  of  the  acetylene,  heating  and 
decomposition  of  the  gas  need  not  be  feared. 

It  may  be  added  that  the  purifying  material  also 
performs  the  function  of  a  filter  in  retaining  the  solid 
particles  of  dust  carried  along  with  the  gas.  It  is 
also  practically  equal  to  the  hydraulic  safety  valve 
as  a  guarantee  of  safety,  since  a  strong  layer  of  pow- 


Figure  23. — Types   of  Purifiers  for   Catalysol 

dered  material  is  interposed  between  the  generat- 
ing apparatus  and  the  piping,  which  effectually  op- 
poses the  return  of  the  flame. 

Such  a  product  should  appeal  with  certain  success 
in  the  economical  complete  purification  of  acetylene 
for  use  in  autogenous  welding. 

Purifiers. — The  purifiers  generally  consist  of  cylin- 
drical vessels  (Figure  23)  made  of  sheet-iron  or  steel 
closed  by  a  cover,  the  joint  being  made  of  rubber.  A 
perforated  plate  with  very  fine  holes  is  supported 
in  the  vessel  at  a  distance  of  2  to  3  inches  from  the 
bottom,  according  to  the  type.  The  gas  arrives  under 


PURIFICATION  OF  ACETYLENE 


the  plate,  and  passes  out  near  the  top  immediately  un- 
der the  cover. 

The  only  conditions  to  observe  when  catalysol  is 
used  are  as  follows: — In  order  to  avoid  loss  of  pres- 
sure with  the  charge  too  high,  the  layer  of  mate- 
rial should  not  exceed  12  inches  depth;  10  inches  is 
more  favorable.  The  purifying  surface  (surface  of 
perforated  plate)  is  calculated  on  the  basis  of  0.5 
cubic  foot  per  hour  for  every  square  inch  of  surface, 
and  for  the  maximum  consumption  of  the  welding 
shop.  With  this  data,  and  knowing  the  density  of 
catalysol,  which  is  from  35  to  45  Ibs.  per  cubic  foot, 
it  is  easy  to  calculate  the  charge  of  purifying  mate- 
rial required  for  a  given  installation. 

TABLE  II. 

DIMENSIONS    AND    CAPACITIES    OF    CATALYSOL,    PURIFIERS 
FOR  WELDING. 


Diameter 
of 
Purifier. 

Height    of 
Purifying 
Material. 

Approxi- 
mate 
Total 
Height    of 
Purifier. 

Maximum 
Delivery   of 
Acetylene 
per  hour. 

Weight   of 
Catalysol 
required. 

inches. 

inches. 

inches. 

litres. 

cubic  feet 

Ibs. 

8 

10 

12y2 

600 

21.2 

11 

11 

10 

13 

1200 

42.4 

22 

14 

10 

13% 

1800 

63.6 

33 

16 

10 

14 

2400 

84.8 

44 

18 

11 

15V2 

3000 

106 

66 

20 

12 

16% 

3800 

135 

88 

22 

12 

16% 

4700 

166 

110 

24 

12 

16% 

5600 

198 

132 

The  cross  section  of  the  passages  through  the  cocks 
and  points  of  the  purifier  should  at  least  equal  in  area 
that  of  the  piping.  If  the  acetylene  is  not  too  highly 
charged  with  water  vapor  it  makes  no  difference  which 
direction  the  gas  passes  through  the  purifier. 


74 


OXY-ACETYLENE  WELDING  AND  CUTTING 


The  placing  of  a  disc  of  felt  or  other  porous  mate- 
rial between  the  perforated  plate  and  the  purifying 
material  enables  the  gas  to  pass  through  better  and 
prevents  material  from  falling  through  the  holes  into 
the  double  bottom.  The  purifying  material  should  be 
simply  poured  in  without  packing  down  except  lightly 
near  the  edges  to  prevent  the  formation  of  passages 
through  the  powder.  The  interior  of  the  purifier  and 


Fig-ure  24. — Position  of  Purifier  with  Regard  to  Acetylene 
Generators 

the  perforated  plate  should  be  carefully  painted  with 
an  adherent  coating,  such  as  coal  tar  applied  warm 
in  order  to  prevent  oxidation  of  the  metal  which 
rapidly  attacks  the  plates  even  when  galvanized  or 
leaded. 

Purifier  Position  and  Maintenance. — The  purifier 
may  be  placed  in  any  position  in  the  piping  between 
the  generator  and  the  place  of  welding.  The  best 
place  is  near  the  generator,  if  there  is  room. 


PURIFICATION  OF  ACETYLENE  75 

Maintenance  simply  cocsists  in  the  replacement  of 
the  purifying  material  when  it  is  destroyed.  The  ex- 
haustion of  the  purifying  powers  of  the  material  is  in- 
dicated by  a  change  in  color  in  the  material  and  in  the 
welding  flame.  The  flame  will  become  yellowish  and 
opaque  in  place  of  the  usual  transparent  blue. 

The  simplest  method  of  testing  the  purification  of 
the  gas  is  to  take  a  10  per  cent  solution  of  nitrate 
of  silver  (obtainable  from  any  druggist)  and  place  a 
drop  of  the  solution  on  a  filter  paper  or  white  blot- 
ting paper.  Place  the  paper  against  the  escaping 
acetylene  and  if  the  paper  turns  black  in  a  few  sec- 
onds it  indicates  that  the  purifying  material  is  use- 
less. If  the  paper  remains  white  the  purifier  is  still 
good.  If  it  blackens  slowly  and  slightly  the  purifier 
is  slightly  exhausted. 

INSTALLATION   AND   MAINTENANCE  OF  THE 
ACETYLENE  PLANT 

Location  of  Plant. — The  best  location  for  an  acet- 
ylene plant  is  in  the  open  air  under  a  roof  or  shed, 
but  this  is  not  always  possible.  A  shed  is  satisfactory, 
provided  it  is  well  ventilated  and  all  precautions  are 
taken  against  carelessness.  If  it  is  impossible  to  find 
such  a  place  then  the  plant  should  be  located  in  the 
best  ventilated  part  of  the  building  and  near  daylight. 

Should  it  be  necessary  to  locate  an  acetylene  plant 
in  the  interior  of  a  building,  it  should  be  isolated 
by  a  partition,  preventing  all  sparks  and  flame  from 
reaching  the  plant.  There  should  also  be  good  circula- 
tion of  air  from  outdoors  to  insure  good  ventilation. 
In  no  case  should  an  acetylene  generator,  even  a  small 
one,  be  located  in  cellars,  poorly  ventilated  places  or 
dwelling  places.  It  should  be  remembered  that  acet- 


76  OXY-ACETYLENE  WELDING  AND  CUTTING 

ylene,  while  not  dangerous  in  itself,  can  form  with 
air  if  escaping,  a  dangerously  explosive  mixture. 

Regulations — Fire  Insurance. — The  manufacture 
and  use  of  acetylene  is  regulated  by  laws  and  by  the 
rules  of  the  National  Board  of  Fire  Underwriters. 
There  are  definite  rules  governing  installation  and  use 
of  the  apparatus,  the  storage  of  carbide,  the  con- 
struction of  generators  and  the  source  of  supply  of 
oxygen  gas. 

It  must  be  possible  for  the  workman  to  reach  any 
part  of  the  apparatus  easily,  the  generator  must  be 
protected  against  freezing,  the  escape  pipe  must  pass 
outside  the  building  and  charging  must  not  be  done 
under  artificial  light  other  than  incandescent  electric 
bulbs  encased  in  safety  globes. 

Carbide  up  to  600  pounds  may  be  kept  in  insured 
buildings  if  in  a  dry,  well  ventilated  place  and  in 
drums  of  not  over  100  pounds  capacity  each.  Only 
one  of  these  drums  may  be  opened  at  one  time.  The 
construction  of  all  standard  generators  that  comply 
with  the  rules  will  be  certified  to  by  a  plate  attached 
to  the  apparatus,  stating  this  fact. 

Charging  and  Cleaning. — It  is  necessary  to  be  per- 
fectly acquainted  with  the  working  and  construction 
of  the  apparatus  and  to  obtain  from  the  manufacturer 
full  and  complete  instructions  relative  to  the  manipu- 
lation of  the  plant. 

The  work  of  charging  and  cleaning  should  be  done 
in  the  day  time  if  possible.  The  generator,  buckets, 
baskets,  etc.,  should  be  cleaned  with  a  strong  flow  of 
water  and  not  recharged  until  they  are  perfectly  dry. 
The  baskets  would  be  better  for  a  second  flow  of  wa- 
ter and  should  never  be  recharged  until  perfectly  dry. 
In  order  to  prevent  the  admission  of  air,  or  at  least 


PURIFICATION  OF  ACETYLENE  77 

to  prevent  any  great  amount  entering  the  generator 
not  provided  with  an  air  cock,  it  is  necessary  in  car- 
bide to  water,  automatic  or  non-automatic  generators 
to  effect  the  emptying  suddenly  by  jerks,  thus  making 
certain  that  a  quantity  of  lime  sludge  flows  out  before 
opening  the  water  valve.  After  each  opening  replace 
with  clean  water  and  repeat.  In  this  way,  effective 
cleaning  takes  place  at  the  time  of  emptying. 

In  water  to  carbide,  dipping  or  immersion  genera- 
tors it  is  sufficient  to  throw  a  small  quantity  of  water 
on  the  chamber  farthest  from  the  generator  door 
just  at  the  moment  the  generator  is  to  be  closed.  This 
produces  enough  gas  to  replace  the  air  in  the  generat- 
ing chamber. 

General  Precautions. — In  case  of  defective  working 
or  sudden  failure  it  is  absolutely  necessary  to  avoid 
going  near  the  generator  with  a  naked  light  or  any 
incandescent  body,  more  especially  if  the  odor  of 
acetylene  is  present. 

In  the  case  of  all  repairs  which  have  to  be  made  to 
the  plant  in  which  a  flame  of  any  kind  is  to  be  used, 
it  is  essential  to  thoroughly  remove  all  gas  or  mix- 
tures of  gas  and  air  from  the  various  parts  of  the 
apparatus.  Remember  that  mixtures  of  10  parts  of 
acetylene  to  90  of  air  are  highly  explosive;  con- 
sequently, it  is  necessary  to  remove  all  traces  of  acet- 
ylene. All  parts  which  are  not  easily  gotten  at  can 
only  be  thoroughly  cleaned  by  thorough  rinsing  re- 
peated two  or  three  times. 

Access  and  working  of  the  generator  should  be  for- 
bidden to  all  persons  who  are  not  charged  with  its 
making.  A  summary  of  the  working  instructions,  both 
for  the  interior  and  exterior,  and  necessary  precau- 
tions, should  be  provided. 


78  OXY-ACETYLENE  WELDING  AND  CUTTING 

Acetylene  Light. — Acetylene  constitutes  a  good 
method  of  lighting  for  work  shops.  Advantage  can 
be  taken  of  the  generating  plant  and  piping.  The 


Figure    25. — Jet    Burner 

piping  and  details  required  are  exactly  the  same  as 
for  coal  gas. 

In  cases  of  general  lighting,  incandescent  burners 
are  used  where  there  is  not  too  much  risk  of  the  man- 
tles being  deteriorated  by  shocks,  dust,  etc.  Those  who 


Figure    26. — Fish-tail    Burner 

nse  autogenous  welding  should  not  ignore  the  fact 
that  acetylene  is  good  for  lighting,  superior  in  many 
cases  to  coal  gas,  electricity,  and  in  many  cases  more 
economical. 

Figures   25,   26   and   27    show   different   styles   of 
burners. 


PURIFICATION  OF  ACETYLENE  79 

DISSOLVED  ACETYLENE 

It  has  already  been  noted  that  compressed  acet- 
ylene, under  the  influence  of  heat  or  shock,  is  liable 
to  decompose  with  violent  explosions.  Liquefied  acet- 
ylene possesses  these  disadvantages  to  an  even  greater 
degree.  Severel  years  ago  inventors  suggested  mak- 
ing use  of  the  solubility  of  acetylene  in  liquids  in 
order  to  store  the  gas  in  portable  form.  To  obtain 
a  great  solubility  the  acetylene  must  be  highly  corn- 


Fig.   27. — Fish-tail  Burner,    Impinging  Type 

pressed,  and  the  properties  of  the  gas  in  the  dis- 
solved state  alter. 

Acetylene  Dissolved  in  Acetone. — Acetone  is  the 
most  satisfactory  liquid  for  dissolving  acetylene  gas. 
Acetone  is  a  colorless  liquid  with  an  ethereal  odor.  It 
boils  at  56°  Cent.  (132.8°  Fahr.) .  One  pint  of  acetone 
weighs  approximately  1  Ib. 

The  coefficient  of  solubility  in  acetone  varies  con- 
siderably with-  the  temperature.  Berthelot  and  Vieille 
have  shown  that  a  vessel  containing  half  the  volume  of 
acetylene  at  an  absolute  pressure  of  16.17  atmospheres 
and  2.8°  Cent.  (37°  Fahr.)  rises  to  33.21  atmospheres 
at  50.5°  Cent.  (122.9°  Fahr.).  Under  ordinary  con- 


SO  OXY-ACETYLENE  WELDING  AND  CUTTING 

ditions  of  use  and  working,  the  initial  pressure  is 
increased  approximately  one-thirtieth  for  each  degree 
Centigrade  rise  of  temperature. 

The  presence  of  water  in  acetone  diminishes  the  co- 
efficient of  solubility.  It  is  therefore  necessary  to  use 
the  purest  acetone  and  to  introduce  the  acetylene  per- 
fectly dry.  Up  to  a  pressure  of  20  atmospheres  to 
the  square  inch  a  solution  of  acetylene  in  acetone  is 
quite  stable. 

Porous  Materials. — However,  the  decomposition  of 
the  gas  under  pressure  is  still  possible,  filling  the  space 
between  the  liquid  and  the  vessel  and  therefore  the 
process  is  not  industrially  applicable. 

All  these  disadvantages  have  been  overcome  by  an 
improved  method  which  consists  of  completely  filling 
the  cylinders  with  a  porous  material  and  then  saturat- 
ing it  with  acetone.  Numerous  experiments  have  shown 
that  up  to  a  pressure  of  515  pounds  per  square  inch 
this  method  is  quite  non-explosive,  not  only  the  solu- 
tion, but  also  the  liberated  gas.  The  decomposition 
provoked  at  any  one  point  in  the  cylinder  can  travel 
only  a  very  short  distance,  producing  an  increase  of 
pressure  scarcely  equal  to  the  original  pressure.  In 
addition  the  porous  material  has  the  advantage  of 
preventing  any  possible  flowing  of  the  liquid.  It 
also  facilitates  dissolution  of  the  gas  and  the  phenom- 
ena of  supersaturation. 

A  number  of  researches  have  been  made  on  the  com- 
position of  porous  materials  suitable  for  filling  the  cyl- 
inders of  dissolved  acetylene  and  numerous  patents 
have  been  secured.  The  material  is  introduced  in  the 
form  of  a  paste  and  the  cylinders  are  then  thoroughly 
dried  by  baking  from  fifteen  days  to  three  weeks. 

Cylinders  of  Dissolved  Acetylene. — The  cylinders 


PURIFICATION  OF  ACETYLENE  81 

are  made  from  steel  plate,  often  by  means  of  autogen- 
ous welding.  These  cylinders  are  completely  filled 
with  porous  material  saturated  with  acetone  to  such 
a  degree  as  to  render  them  non-explosive.  The  porous 
material  completely  absorbs  the  acetone,  so  that  it  is 
impossible  for  the  acetone  to  run  out,  no  matter  in 
what  position  the  cylinder  may  be  placed. 

These  cylinders  are  tested  at  a  pressure  several 


Figure   28. — Cylinder   of  Dissolved  Acetylene 

times  that  to  which  the  vessel  will  be  subjected  while 
in  use.  The  necessity  for  renewing  the  porous  mate- 
rial may  be  ascertained  by  testing  the  cylinders.  For 
the  purpose  of  dissolved  acetylene,  the  gas  is  pre- 
pared in  a  generator  under  the  best  possible  condi- 
tions. It  is  chemically  purified  and  conveyed  to  a 
gasometer  for  cooling.  The  gas  is  then  compressed 
into  the  cylinders  containing  the  porous  material  sat- 
urated with  acetone. 


82  OXY-ACETYLENE  WELDING  AND  CUTTING 

Contents  of  the  Cylinders. — The  volume  of  the  cyl- 
inders varies,  the  cylinders  usually  employed  for  weld- 
ing containing  from  100  to  200  cubic  feet  of  gas.  As 
a  general  rule  one  cubic  foot  of  porous  material  at  a 
pressure  of  150  Ibs.  per  square  inch  will  carry  100 
cubic  feet  of  gas. 

The  nominal  capacity  is  only  approximate  as  the 
dimensions  of  the  cylinders  and  the  weight  of  acetone 
which  the  cylinder  contains  varies.  Moreover,  the 
solubility  in  acetone  varies  with  the  temperature,  so 
that  the  pressure  gauge  gives  different  readings 
according  to  whether  the  cylinder  is  warm  or  cold. 

The  only  accurate  test  to  verify  the  contents  of 
the  bottle  under  pressure  is  to  weigh  the  bottJe  (1) 
charged  with  acetylene;  (2)  empty  of  acetylene.  The 
difference  gives  the  weight  of  acetylene  used. 

One  cubic  foot  of  acetylene  weighs  0.074  Ib. 
and  1  pound  occupies  a  space  of  13.6  cubic  feet. 
Therefore,  to  obtain  the  net  volume  of  gas  in  the  cyl- 
inder, multiply  the  difference  in  weight  when  full 
and  empty  by  13.6.  As  an  example  let  the  weight  of 
the  full  cylinder  be  102!/2  Ibs.  and  the  weight  empty 
be  95  Ibs.  The  difference  is  iy2  Ibs.,  which  multiplied 
by  13.6  gives  102  cubic  feet  as  the  actual  contents  at 
32°  Fahr.  The  volume  at  normal  temperatures 
would  be  increased  above  this  value. 

Use  of  Cylinders. — The  cylinders  of  dissolved  acet- 
ylene are  provided  with  a  valve  opened  with  a  detach- 
able key.  The  valve  fitting  carries  a  thread  for  at- 
taching the  reducing  valve  to  the  cylinder.  The  use 
of  a  reducing  valve  is  necessary  for  two  reasons.  (1) 
It  is  possible  to  know  the  pressure  at  any  time,  and 
(2)  the  amount  of  pressure  may  be  regulated  to  the 
best  point. 


PURIFICATION  OF  ACETYLENE  83 

Advantages  of  Dissolved  Acetylene. — The  use  of 
dissolved  acetylene  for  autogenous  welding  has  many 
advantages,  among  which  are : 

(1)  No  generating  apparatus  and  accessories  re- 
quired. 

(2)  Portability. 

(3)  Use  of  high  pressure  blowpipes  possible. 

(4)  Perfectly  pure  acetylene. 

These  qualities  are  so  important  that  dissolved  acet- 
ylene would  always  be  used  were  it  not  for  the  fact 
that  its  cost  is  much  higher. 

On  the  contrary,  the  use  of  dissolved  acetylene  is 
always  to  be  adopted  where  the  cost  of  gas  does  not 
enter  into  the  question,  such  as  certain  repairing  jobs 
in  shipyards,  that  is,  outside  workshops  where,  na- 
turally, cylinders  are  more  convenient  than  fixed  or 
portable  plant.  In  the  case  of  the  repairs  to  boilers 
and  others  which  require  perfect  welds  and  which 
cannot  be  carried  out  in  the  work  shop,  the  use  of  dis- 
solved acetylene  should  be  insisted  on  for  the  reason 
that  small  portable  plants  cannot  supply  the  gas  un- 
der as  good  conditions  of  purity,  pressure,  etc. 

Manipulations  and  Precautions. — The  cylinders  of 
dissolved  acetylene  can  be  manipulated  without  any 
special  precautions.  The  welder  simply  avoids  their 
deterioration  by  violent  shocks,  falls,  etc.  The  part 
which  supports  the  valve  should  be  particularly  looked 
after. 

The  dissolved  acetylene  cylinders  are  not  affected 
by  lowering  of  temperature,  therefore  one  can  leave 
them  exposed  to  cold  in  all  seasons  and  in  all  countries. 
On  the  contrary,  one  should  avoid  leaving  them  in  a 
heated  atmosphere. 

Care  should  be  taken  that  there  is  no  leak  between 


84  OXY-ACETYLENE  WELDING  AND  CUTTING 

the  valve  and  the  reducing  valve  or  in  the  reducing 
valve  itself ;  all  flames  on  the  bottle,  or  in  its  neighbor- 
hood, should  be  extinguished  as  soon  as  possible ;  and 
the  valve  of  the  bottle  should  be  closed  after  using. 
Lastly,  the  usual  necessary  precautions  should  be  taken 
in  the  case  of  gases  and  inflammable  vapors. 


CHAPTER  VI 

OXY-ACETYLENE   TORCHES 

The  oxy-acetylene  blowpipe,  or  torch,  intended  for 
autogenous  welding  is  an  instrument  of  precision,  yet 
extremely  simple,  of  light  weight  and  easy  to  handle. 
It  mixes  the  oxygen  and  acetylene  in  just  the  right 
proportions.  Figure  29  is  a  sectional  view  showing 
the  general  principles  on  which  the  torch  operates. 
The  mixture  escapes  through  the  exit  nozzle  and,  upon 


Exrr  i 

Figure    29. — Section    of    Oxy-acetylene    Blowpipe 

being  lighted,  produces  a  flame  which  is  steady  and 
of  suitable  dimensions  for  the  purpose  of  welding. 

As  shown  in  Figure  29,  the  torch  usually  consists 
of  a  central  body  or  handle,  at  one  end  of  which  the 
two  gases  enter,  and  at  the  other  end  of  which  is  the 
mixing  chamber  which  bends  toward  the  nozzle.  For 
ease  of  manipulation  during  welding  the  torch  is  bent 
at  the  nozzle  and  to  an  angle  suitable  for  directing 
and  observing  the  flame  and  its  action. 

According  to  the  pattern  and  consumption  of  gas 
the  lengths  of  blowpipes  vary  from  1  to  2%  feet  and 
their  weights  range  from  1  to  4%  pounds.  They  are 
generally  made  of  brass  while  the  nozzle  or  tip  is 
made  of  red  copper.  They  are  made  in  various  capac- 
ities corresponding  to  an  hourly  use  of  from  1  to  100 

85 


86  OXY-ACETYLENE  WELDING  AND  CUTTING 

cubic  feet  of  acetylene  and  appropriate  for  welding 
metals  of  all  thicknesses. 

Requirements. — The  blowpipe  should  be  as  safe  as 
it  can  possibly  be  made  even  in  the  hands  of  careless 
or  unskilled  operators.  It  should  be  simple,  easily  di- 
rected and  should  supply  a  steady  flame.  The  con- 
sumption of  acetylene  and  oxygen  should  be  as  nearly 
alike  as  possible. 

These  conditions  are  much  more  difficult  to  realize 
than  appears,  especially  in  the  case  of  torches  in  which 
the  acetylene  is  admitted  at  the  pressure  of  genera- 
tion; that  is  to  say,  practically  no  pressure. 

The  chief  difficulty  to  be  overcome  is  to  obtain 
the  necessary  stability  of  flame.  The  velocity  of  propa- 
gation of  the  flame  in  the  case  of  a  mixture  of  oxy- 
gen and  acetylene  is  about  330  feet  per  second.  It 
is  therefore  necessary,  in  order  to  avoid  the  striking 
back  of  the  flame,  that  the  velocity  of  the  mixture 
at  the  exit  should  be  of  the  same  value,  or  at  least 
such  that  it  constantly  prevents  the  return  of  the 
flame  to  the  interior. 

Of  course  with  the  oxygen  being  stored  under  great 
pressure  it  is  always  possible  to  obtain  a  high  velocity 
through  the  nozzle,  but  for  reasons  wliich  it  would 
take  too  long  to  explain  here,  the  proper  working  of 
the  blowpipe  requires  the  oxygen  under  the  most 
feeble  pressure  possible.  This  pressure  is  almost  en- 
tirely used  in  aspirating  the  acetylene  and  insuring 
a  sufficient  exit  velocity  to  the  gas.  The  arrange- 
ment necessary  to  obtain  this  demands  serious  study. 

The  intimate  mixture  of  the  gases  should  be  per- 
fectly accomplished  before  their  escape  from  the  blow- 
pipe. This  consideration,  which  it  is  so  important  to 
obtain,  is  difficult  to  realize,  because  it  is  necessary  to 


OXY-ACETYLENE  TORCHES  87 

avoid  too  much  loss  of  pressure,  which  would  require 
an  increase  in  the  pressure  of  the  oxygen  in  order  to 
regain  the  velocity  through  the  nozzle  which  is  neces- 
sary for  the  stability  of  the  flame.  The  prevention  of 
the  return  of  the  flame  into  the  mixing  chamber,  which 
return  is  made  easier  as  the  torch  heats  up  and  as 
sparks  fly  around  the  nozzle,  requires  serious  study. 

Lastly,  a  large  number  of  details  merit  attention,  as 
for  instance,  the  construction  of  the  nozzle,  ease  of 
manipulation,  cross  sections  of  the  several  parts,  ease 
of  taking  to  pieces  and  reassembling,  and,  in  fact, 
a  torch  which  appears  such  a  common  article  requires 
such  precision  in  construction  that  it  is  only  to  be 
undertaken  by  specialists  in  the  subject.  The  work- 
ing and  yield  of  different  blowpipes  can  be  compared 
by  the  stability  of  the  flame,  consumption  of  oxygen, 
etc.  It  is  necessary  to  leave  to  specialists  and  experts 
the  care  and  construction  and  even  the  repair  of  blow- 
pipes, because  the  economy  and  good  results  of  weld- 
ing depend  more  on  this  than  is  generally  thought. 

Classification. — Oxy-acetylene  "blowpipes  vary  ac- 
cording to  the  pressure  of  acetylene,  as  we  know  that 
oxygen  can  be  used  without  limit  of  pressure. 

Blowpipes  can  be  divided  into  three  principal 
classes : — 

(1)  Blowpipes  for  high  pressure  acetylene. 

(2)  Blowpipes  for  medium  pressure  acetylene. 

(3)  Blowpipes  for  low  pressure  acetylene. 

The  meaning  of  the  terms,  high,  medium  and  low 
pressure  is  as  follows :  high  pressure  implies  more 
than  15  pounds  to  the  square  inch;  medium  pres- 
sure implies  not  more  than  15  pounds  per  square 
inch ;  low  pressure  applies  to  systems  using  not  to  ex- 
ceed 1  pound  per  square  inch. 


88  OXY-ACETYLENE  WELDING  AND  CUTTING 

The  delivery  and  power  of  the  torch  may  be  varied 
in  high  and  medium  pressure  types  by  simply  chang- 
ing the  nozzle  or  by  regulating  the  openings  which 
admit  the  gas.  In  low  pressure  the  delivery  is  fixed 
because  there  is  a  suitable  oxygen  injector  and  nozzle 
for  each  case. 

Low  pressure  blowpipes  have  been  made  which  by 
the  changing  of  a  portion  containing  the  nozzle,  in- 
jector and  mixing  chamber,  can  be  made  to  furnish 
different  powers.  This  makes : — 

(a)  Torches  for  low  pressure  acetylene  with  fixed 
delivery;  and  (b)  torches  for  low  pressure  acetylene 
with  variable  delivery. 

Lastly,  low  pressure  torches  have  been  designed  for 
variable  delivery  by  regulating  the  oxygen  injector 
according  to  the  size  of  the  nozzle,  this  being  accom- 
plished by  means  of  devices  for  reducing  the  section 
through  which  the  gas  flows.  These  latter  may  be 
called  torches  for  low  pressure  acetylene  with  oxygen 
regulator.  It  should  be  noted  that  blowpipes  con- 
structed for  using  acetylene  at  low  pressure  can  also 
work  with  medium  or  high  pressure  acetylene  by  re- 
ducing proportionately  the  pressure  of  the  oxygen. 
On  the  other  hand,  blowpipes  for  medium  and  high 
pressures  cannot  be  used  for  low  pressure  acetylene. 

Torches  for  High  Pressure  Acetylene. — These  work 
with  practically  equal  pressures  of  oxygen  and  acet- 
ylene, which  makes  their  construction  quite  simple. 
The  gases  arrive  by  different  tubes,  one  generally  sur- 
rounding the  other  in  the  torch,  and  are  intimately 
mixed  in  the  tubes  while  being  carried  to  the  nozzle. 
The  regulation  is  obtained  by  valves  placed  on  the 
torch  or  by  the  reducing  valves  at  the  cylinders. 

The  acetylene  and  oxygen  being  used  at  practically 


OXY-ACETYLENE  TORCHES  89 

the  same  pressures,  there  cannot  be  a  return  of  one 
gas  into  the  tube  used  by  the  other.  To  prevent  the 
flame  from  running  back  toward  the  source  of  acet- 
ylene, a  screen  of  porous  material  is  interposed  im- 
mediately after  entering  the  blowpipe.  This  allows 
the  gas  to  pass  through  easily,  but  prevents  passage  of 
flame.  The  torch  shown  in  Figure  30  shows  this  screen 


Figure  30. — Section  of  a  High  Pressure  Blowpipe 

made  of  aluminum  shavings,  also  the  valve  for  regu- 
lating the  oxygen  with  the  hand  holding  the  torch. 

In  order  to  vary  the  power  of  the  flame  it  is  only 
necessary  to  change  the  nozzle.  These  are  made  in 
various  sizes  for  different  deliveries,  Figure  31  show- 
ing a  torch  with  several  nozzles.  Having  selected 
the  proper  nozzle  size  it  is  only  necessary  to  regulate 
the  admission  of  the  gases. 


Figure   31. — Blowpipe   for   High    Pressure,    with   Nozzles 

If  the  gas  issues  from  the  nozzle  faster  than  the 
speed  at  which  this  form  of  flame  can  travel,  stable 
combustion  cannot  take  place  directly  at  the  nozzle 
tip.  Normal  working  of  the  flame  takes  place  between 
fairly  fixed  limits  of  pressure  which  are  easily  main- 
tained by  the  reducing  valves.  These  pressures  in- 
crease with  the  power  of  the  torch,  being  always  suf- 
ficient to  approximately  equal  the  speed  of  the  flame. 


90  OXY-ACETYLENE  WELDING  AND  CUTTING 

Torches  for  Medium  Pressure  Acetylene. — Acet- 
ylene cannot  be  obtained  industrially  from  gener- 
ators at  a  sufficiently  high  pressure  to  use  the  blow- 
pipes that  have  just- been  described;  therefore,  the  best 
that  can  be  done  is  to  store  the  acetylene  in  gasometers 
having  a  pressure  from  40  to  80  inches  of  water.  Thus 
used,  the  acetylene  does  not  require  a  much  higher 
pressure  of  oxygen  to  give  the  mixture  sufficient  veloc- 
ity. 

An  injector  through  which  the  oxygen  escapes  at  a 
pressure  slightly  in  excess  of  the  acetylene  is  sufficient 
to  give  the  necessary  speed. 

The  injector  nozzle  of  the  oxygen  remains  the  same 
whatever  be  the  delivery  of  the  blowpipe  nozzle.  It  is 
only  necessary  to  change  the  blowpipe  nozzle  to  vary 
the  power  of  the  flame.  The  regulation  is  done  by  the 
cock  controlling  the  gas  or  by  the  reducing  valve  on 
the  oxygen  bottle. 

The  principle  of  blowpipes  for  medium  pressure  is 
almost  the  same  as  for  blowpipes  using  dissolved  acet- 
ylene, except  that  the  oxygen  is  used  at  a  slightly 
higher  pressure  than  the  acetylene,  which  necessitates 
a  slight  modification  in  the  arrangement. 

Torches  for  Low  Pressure  Acetylene  and  Fixed 
Delivery. — The  majority  of  acetylene  generators  de- 
liver the  gas  at  a  pressure  but  little  above  the  atmos- 
phere. In  order  to  obtain  sufficient  velocity  at  the 
nozzle,  which  is  necessary  for  proper  working,  the  oxy- 
gen must  be  used  at  a  comparatively  high  pressure. 

This  meeting  of  the  two  gases  in  the  torch,  one  at 
high  speed  and  the  other  at  low  speed  and  pressure, 
requires  special  devices.  In  order  that  the  mixture 
may  take  place,  the  acetylene  must  flow  into  a  tube 
while  the  oxygen  is  rushing  into  the  same  tube  at  a 


OXY-ACETYLENE  TORCHES  91 

high  speed.  This  results  in  the  acetylene  being  sucked 
in  by  the  oxygen.  The  higher  the  pressure  of  the 
acetylene  the  less  effort  will  be  required  from  the  oxy- 
gen and  vice  versa. 

Injector  Action. — The  suction  of  acetylene  by  the 
oxygen  is  produced  by  a  device  known  as  the  injector. 
This  works  on  the  same  principle  as  a  steam  injector, 
except  that  oxygen  is  used  in  place  of  steam. 

The  injector  nozzle  opens  in  a  conical  portion, 
where  it  draws  in  the  combustible  gas.  The  mixed 
gases  are  then  ejected  through  an  expansion  chamber 


Figure   32.— Fouch£   Blowpipe 


where  the  velocity  is  reduced  to  a  suitable  value.  The 
proportions  and  arrangements  of  the  various  details 
have  to  be  carefully  worked  out  for  each  case. 

It  is  clear  that  the  delivery  of  oxygen  being  fixed 
by  the  size  of  the  injector  orifice,  the  power  of  the 
blowpipe  is  invariable  in  these  limits,  and  in  practice 
variation  of  pressure  clearly  means  bad  working. 

Therefore,  according  to  the  number  of  powers  of 
flame  required,  one  should  possess  blowpipes,  gen- 
erally 5  to  10,  for  obtaining  the  whole  range  of  deliv- 
eries ;  that  is  to  say,  from  1.75  to  2.65  cubic  feet  per 
hour  to  70  to  90  cubic  feet. 

The  orifice  at  the  nozzle  of  the  blowpipe  for  low 
pressure  acetylene  is  designed  according  to  the  de- 
livery of  the  injector  when  using1  the  oxygen  at  a 


92  OXY-ACETYLENE  WELDING  AND  CUTTING 

pressure  for  which  it  has  been  designed.     It  is  there- 
fore essential  that  it  be  neither  reduced  nor  enlarged. 
The  first  inventors  of  low  pressure  acetylene  blow- 


Figure   33. — Section   of   Fouche   Blowpipe 


pipes  strongly  feared  the  striking  back  of  the  flame 
into  the  tube  containing  the  acetylene,  as  for  example 
when  the  exit  of  the  nozzle  became  obstructed.  In 


Figure   34. — Simple    Torch 


order  to  avoid  this  they  invented  many  ingenious 
devices  which  are  now  known  not  to  be  indispensable, 
since  the  tube  which  brings  the  acetylene  from  the 


Figure  35. — Section  of  Weber  Torch 


cock  of  the  blowpipe  to  the  injector  arrangement  does 
not  offer  a  sufficient  explosive  capacity,  and  a  safety 
arrangement  placed  at  the  extremity  of  the  acetylene 
piping  prevents  the  passage  of  the  oxygen  into  the 
latter. 


OXY-ACETYLENE  TORCHES 


93 


A  good  idea  of  the  many  low  pressure  acetylene 
torches  for  fixed  delivery  and  their  construction  can. 
be  had  by  a  study  of  Figures  33  to  38. 


Figure  36. — Section  of  Columbia  Blowpipe 

Torches  for  Low  Pressure  Acetylene  and  Variable 
Delivery. — In  torches  of  fixed  delivery,  if  it  is  a  ques- 
tion of  making  the  power  variable,  it  would  be  neces- 


Figure   37. — Section   of  Cyclop  Blowpipe 


sary  to  provide  for  the  simultaneous  changing  of  the 
oxygen  injector,  the  mixing  chamber  and  the  nozzle. 
A  type  of  variable  delivery  torch  has  been  recently 


Figure    38. — Blowpipe    with    Interchangeable    Heads 

invented  and  has  attained  success.  The  inventor  of 
the  oxygen  injector  found  that  variable  action  might 
be  secured  by  means  of  a  needle  valve  controlling  the 


94  OXY-ACETYLENE  WELDING  AND  CUTTING 

opening.  This  principle  has  been  used  by  placing  a 
nozzle  suited  for  the  required  delivery  on  the  torch 
and  then  adjusting  the  injector  needle  valve  to  this 
nozzle  and  delivery.  By  so  doing  one  torch  of  this 
pattern  can  be  made  to  furnish  a  large  variety  of 


Figure  39. — Picard  Blowpipe  with  the  Oxygen  Regulator 

flames.  This  regulation  of  the  oxygen  is  made  by 
a  small  milled  wheel  controlling  the  needle  valve  so 
that  the  valve  may  be  almost  completely  closed  or 
entirely  opened. 

In  order  to  obtain  good  results,  the  details  and  the 
regulator  must  be  well  made.     The  oxygen  enters  the 


Figure  40. — Section  of  Essential  Details  of  Picard  Blowpipe 

injector  chamber  in  an  annular  jet  and  the  suction 
of  acetylene  and  mixing  of  the  gases  takes  place  as  in 
the  types  previously  described.  Final  regulation  of 
the  flame  by  the  oxygen  regulator  is  preferable. 

This  type  of  torch  offers  advantages  over  other  sys- 
tems of  low  pressure,  although  good  construction  and 


OXY-ACETYLENE  TORCHES 


95 


^ 


Ul 


96  OXY-ACETYLENE  WELDING  AND  CUTTING 

perfect  regulation  are  indispensable,  while  its  handling 
and  maintenance  are  quite  difficult  without  practice. 

Figure  41  shows  three  different  sizes  of  torches. 
The  number  5  torch  is  designed  especially  for  jewelers ' 
work  and  chin  sheet  steel  welding.  It  is  11  inches  in 


432' 

Figure    42. — Cox   Welding   Torch    (No.    1) 

length  and  weighs  19  ounces.  The  tips  for  the  num- 
ber 10  torch  are  interchangeable  with  the  number  5. 
The  number  10  torch  is  adapted  for  general  use  on 
light  and  medium  heavy  work.  It  has  six  tips  and  its 
length  is  16  inches  with  a  weight  of  23  ounces. 


986 

Figure    43.— Cox   Welding   Torch    (No.    2) 

The  number  15  torch  is  designed  for  heavy  work, 
being  25  inches  in  length,  permitting  the  operator 
to  stand  away  from  the  heat  of  the  metal  being 
worked.  These  heavy  tips  are  in  two  parts,  the  oxygen 
check  being  renewable. 

Welding   Torches. — Figures  42   and  43   show  two 


OXY- ACETYLENE  TORCHES 


97 


sizes  of  another  welding  torch.  Still  another  type  is 
shown  in  Figure  44  with  four  interchangeable  tips, 
the  function  of  each  being  as  follows : — 

No.  1.     For  heavy  castings. 

No.  2.     Light  castings  and  heavy  sheet  metal. 

No.  3.     Light  sheet  metal. 

No.  4.     Very  light  sheet  metal  and  wire. 

Manufacturers  have  perfected  an  extremely  small 


Figure    44. — Monarch   Welding"   Torch 

torch  designed  for  jewelers  and  others  needing  a  very 
hot,  yet  small  and  concentrated  flame.  It  developes  a 
neutral  flame  but  little  larger  than  a  hair  or  pin  point, 
yet  having  5000°  Fahr.  of  heat. 


CHAPTER  VII 

CHARACTERISTICS   OP   WELDING  TORCHES 

The  power  or  capacity  of  torches  is  based  upon 
their  hourly  consumption  of  acetylene.  The  largest 
use  up  to  140  cubic  feet  per  hour.  Lower  powers  use 
from  3  to  25  feet  per  hour,  or  even  less  in  some  cases. 
The  consumption  of  oxygen  compared  to  that  of  acet- 
ylene should  receive  attention.  Theoretically,  the  for- 
mation of  the  small  welding  jet  requires  exactly  equal 
volumes  of  the  two  gases. 

While  this  result  may  be  approximately  obtained  in 
practice  with  high  pressure  torches,  it  is  only  ap- 
proached with  medium  and  low  pressure  outfits.  All 
experiments  on  torches  of  high  pressure  show  that  the 
respective  volumes  of  the  gases  are  about  equal  pro- 
vided the  operators  are  competent. 

Torches  of  medium  pressure  will  give  almost  iden- 
tical results  if  the  pressure  of  the  acetylene  is  kept 
practically  constant  and  provided  the  oxygen  pres- 
sure is  not  forced  to  attain  too  high  velocity.  All 
researches  do  not  agree,  but  there  is  no  very  great 
difference  between  the  volume  of  oxygen  and  that  of 
acetylene  used. 

Torches  for  low  pressure  acetylene  are  those  with 
which  the  most  difficulty  has  been  experienced  in  this 
respect  of  equal  volumes.  The  oxygen,  being  used 
under  high  pressure,  is  difficult  to  mix  with  the 
acetylene  while  giving  sufficient  velocity.  There  is 
evidently  an  energetic  mixing  of  the  two  gases,  but 
not  properly  diffused  and  homogeneous,  stream  lines 
of  each  gas  escaping  at  the  nozzle. 

98 


CHARACTERISTICS  OF  WELDING  TORCHES  99 

This  may  be  tested  in  various  ways,  for  example, 
by  contracting  the  exit  from  the  mixing  chamber  or 
by  increasing  the  pressure  of  the  oxygen.  In  both 
cases  the  proportion  of  oxygen  to  acetylene  is  con- 
siderably increased.  It  might  be  concluded  from  this 
that  a  torch  for  low  pressure  acetylene  consumes  the 
least  oxygen  when  the  admission  pressure  of  the  latter 
is  lowest  and  the  mixing  arrangements  the  best. 

It  should  be  remarked  that  in  certain  types  of  blow- 
pipes the  oxygen  pressure  to  be  used  corresponds  ex- 
actly with  the  arrangement  of  the  mixing  chamber. 
Change  of  section,  abrupt  bending,  etc.,  can  produce 
a  loss  of  pressure.  It  is  evidently  necessary  to  find  an 
equilibrium  between  these  two  factors,  which  are  oppo- 
site. If  the  pressure  of  the  oxygen  is  not  raised  too 
high,  and  the  arrangement  for  mixing  excellent,  the 
result  may  be  perfect. 

In  a  series  of  experiments  carried  out  with  blow- 
pipes for  low  pressure  acetylene,  the  following  results, 
have  been  obtained  which  give  the  proportion  between 

the  volumes  of  the  oxygen  and  of  the  acetylene,  7^-5" 

^2M± 

The  letters  A,  B,  C,  etc.,  indicate  the  different  types 
of  blowpipe  used. 

Blowpipe  A  (23  cu.  ft.),  shortly  after  ignition  1.4, 
very  warm  1.8. 

Blowpipe  B  (8  cu.  ft.),  shortly  after  ignition  1.35, 
very  warm  1.67. 

Blowpipe  C  (15  cu.  ft.),  shortly  after  ignition  1.60, 
very  warm  1.90. 

Blowpipe  D  (20  cu.  ft.),  shortly  after  ignition  1.65, 
very  warm  1.90. 

Blowpipe  F  (23  cu.  ft.),  shortly  after  ignition  1.45, 
verv  warm  1.55. 


100  OXY-ACETYLENE  WELDING  AND  CUTTING 

Blowpipe  F  (30  cu.  ft.),  shortly  after  ignition  1.55, 
very  warm  1.75. 

These  experiments  were  carried  out  with  the  best 
types  of  blowpipes,  the  admission  pressure  of  the  oxy- 
gen being  that  indicated  by  the  makers  in  their  cata- 
logues, and  the  general  regulation  being  according  to 
their  instructions. 

The  considerable  increase  in  the  consumption  of 
oxygen  on  the  blowpipe  becoming  heated  should  be 
noted.  This  only  occurs  in  blowpipes  using  low  pres- 
sure acetylene.  The  effect  of  expansion  on  the  two 
gases  admitted  at  different  pressures  is  not  the  same, 
but  it  is  relatively  easy  to  obviate  this  disadvantage, 
as  will  be  shown  later  in  the  section  "Regulating  the 
Flame." 

Recent  results  of  fifty  industrial  tests  showed  the 
exact  volume  of  acetylene  and  oxygen  consumed.  The 
blowpipes  used  were  of  many  types;  the  average 
delivery  of  acetylene  was  fixed  at  12.3  cu.  feet  per 
hour,  and  the  "work  to  be  executed  lasted  30  to  40 
minutes.  The  best  proportion  of  oxygen  to  acetylene 
was  1.12,  the  average  was  1.3  and  the  worst  1.9. 

It  was  also  shown  that,  with  the  same  blowpipe  used 
by  two  welders,  one  using  oxygen  at  28  pounds  pres- 
sure and  the  other  at  13  pounds,  that  the  proportion 
in  the  first  case  was  1.83  and  in  the  second  1.25,  clearly 
showing  the  bad  influence  of  excess  pressure  of  oxygen 
on  the  consumption  of  that  gas.  It  is  important  to 
^note  that  the  consumption  of  oxygen  for  a  constant 
delivery  of  acetylene  can  vary  greatly  and  can  even 
double  in  volume,  depending  on  the  type  of  torch  and 
the  conditions  of  use.  Not  only  is  the  oxygen  con- 
sumed in  excess  of  the  theoretical  amount  a  definite 
loss,  but  its  presence  in  the  flame  burns  the  metal, 


CHARACTERISTICS  OF  WELBLNG  TORCHES  ,          101 


lowering  the  strength  of  the  weld  and  making  it 
brittle  and  porous.  These  considerations  are  very 
important  from  two  viewpoints,  economy  and  good 
work. 

TABLE  III. 

COMPARATIVE  CONSUMPTION  OF  OXYGEN  AND  ACETYLENE 
IN  VARIOUS  SIZE  NOZZLES 


Tips 
Used 

Consumption 
of  Oxygen 
per  hr. 

Consumption 
of  Acety- 
lene per  hr. 

Tips 
Used 

Consumption 
of  Oxygen 
per  hr. 

Consumption 
of  Acety- 
lene per  hr. 

1 

3.50  ft. 

3.45  ft. 

6 

28.00  ft. 

24.00  ft. 

2 

5.26  ft. 

4.25  ft. 

7 

37.70  ft. 

33.00  ft. 

3 

9.  00.  ft. 

8.27  ft. 

8 

47.74  ft. 

41.84  ft. 

4 

14.25  ft. 

12.00  ft. 

9 

65.81  ft. 

56.72  ft. 

5 

21.00  ft. 

17.26  ft. 

10 

£3.97  ft. 

82.47  ft. 

Choice  of  a  Torch. — The  choice  of  torches,  especially 
for  low  pressure,  is  a  matter  of  importance.  As  has 
already  been  remarked,  there  are  three  different  types 
of  installations — high,  medium  and  low  pressure.  The 
high  pressure,  using  dissolved  acetylene,  is  the  simplest 
installation;  it  is  portable,  consisting  of  but  two 
cylinders  with  their  regulating  valves,  piping  and  the 
one  torch  which  may  be  varied  in  power  by  changing 
nozzles.  Using  a  good  blowpipe  with  this  system, 
welds  are  obtained  under  the  best  possible  conditions. 

On  the  other  hand,  acetylene  dissolved  in  acetone  is 
much  dearer,  costing  often  two  to  five  times  as  much 
as  the  gas  produced  in  generators,  and  this  is  the  only 
fault  of  the  system. 

According  to  the  kind  of  welds  required,  the  use  of 
dissolved  acetylene  installations  should  be  given  pre- 
cedence where  recommendable ;  that  is,  whether  the 
nature  of  the  work  is  of  first  importance,  or  the  cost  of 


102  OXY-AG^T-YL^ENE  WFJLDI'NG  AND  CUTTING 

the  same.  The  following  are  common  examples  where 
dissolved  acetylene  can  be  used  advantageously: — Re- 
pairs on  board  ships  and  similar  work  in  shipyards; 
garages  for  automobiles,  mechanics'  workshop,  mills, 
etc.,  and  in  all  cases  where  the  application  of  auto- 
genous welding  is  intermittent. 

In  certain  large  workshops  where  autogenous  weld- 
ing is  used  on  a  large  scale  it  pays  to  manufacture 
dissolved  acetylene  on  the  spot,  as  this  can  be  done 
without  a  large  increase  in  price  and  permits  of  chang- 
ing the  place  of  welding,  also  using  blowpipes  for  high 
pressure. 

After  compression  the  acetylene  can  be  distributed 
under  a  pressure  of  120  to  160  inches  of  water  to  the 
welding  places  by  means  of  piping.  Such  installations 
should  be  carefully  studied,  and  should  not  be  used 
unless  there  is  a  very  large  consumption. 

Medium  Pressure. — The  installations  of  medium 
pressure  require  a  special  acetylene  generator  to  pro- 
duce the  gas  at  a  pressure  of  50  to  80  inches  of  water ; 
also  a  hydraulic  safety  valve  specially  constructed  for 
,  the  pressure.  It  is  then  a  question  in  this  case  of 
apparatus  specially  constructed  for  medium  pressure: 
generator,  hydraulic  valve,  blowpipe,  and  these  can- 
not be  used  for  other  purposes.  Manufacturers  do 
not  like  to  acquire  installations  which  cannot  be  modi- 
fied, perfected,  or  added  to  without  applying  to  the 
firm  that  supplied  it.  On  the  other  hand,  the  guar- 
antees given  are  satisfactory. 

The  use  of  medium  pressure  gives  results  which  are 
extremely  favorable  from  the  point  of  view  we  have 
studied  above,  and  the  installation  of  this  type  should 
be  considered  when  choosing  a  system  of  welding. 

Low  Pressure. — The  installations  of  low  pressure 


CHARACTERISTICS  OF  WELDING  TORCHES  103 

are  those  which  are  the  most  numerous ;  using  the  gas 
and  generating  it  at  a  pressure  of  a  few  inches  of 
water.  We  have  stated  previously  the  considerations 
which  are  useful  in  the  choice  of  an  acetylene  gen- 
erator, but  the  choice  of  the  blowpipe  opens  up  the 
question  again,  and  the  type  of  installation  becomes  a 
question  of  great  importance. 

Many  types  of  low  pressure  acetylene  blowpipes  are 
offered  to  the  purchaser,  and  good  quality  can  be 
obtained  in  all  types. 

Let  us  note,  first  of  all,  that  each  blowpipe  has  its 
particular  function  and  aim.  Existing  blowpipes  can 
be  fairly  clearly  classified  according  to  their  logical 
use,  and  corresponding  to  the  particular  ideas  of  their 
inventor. 

There  are  torches  with  fixed  delivery,  others  with 
variable  delivery,  the  good  and  the  bad,  the  light  and 
the  heavy,  the  long  and  the  short.  The  choice  depends, 
first  of  all,  on  the  use  which  is  going  to  be  made  of  the 
torch.  If  it  is  to  continually  weld  identical  pieces  of 
work,  or  if  the  welds  require  the  same  power  of  flame, 
then  it  is  well  to  choose  a  torch  of  fixed  delivery. 

If,  on  the  other  hand,  all  kinds  of  welds  are  to  be 
made,  the  torch  should  be  of  the  variable  delivery 
type.  In  indicating  certain  directions  of  choice  be- 
tween different  types,  it  should  be  remembered  that 
special  conditions  may  vary.  For  instance,  torches  of 
fixed  delivery  are  always  to  be  preferred  as  being 
stronger,  if  the  cost  of  a  series  of  different  sizes  is 
not  a  serious  matter.  On  the  contrary,  the  small  user, 
whose  expenditure  for  tools  is  limited,  should  adopt 
the  system  of  variable  delivery,  which  offers  him  sev- 
eral torches  in  one. 

Weight. — The  weight  of  the  torch  becomes  an  import- 


104  OXY-ACETYLENE  WELDING  AND  CUTTING 

ant  consideration  in  practical  use.  Welders  say  that 
the  best  torches  are  those  that ' '  feel  best  in  the  hand, ' ' 
but  the  choice  depends  upon  the  work  to  be  done  and 
the  length  of  time  the  torch  must  be  held.  If  it  is  a 
case  of  repair  work  which  must  be  done  quickly,  then 
heaviness  of  the  torch  is  not  such  a  serious  objection. 
On  the  other  hand,  if  it  is  construction  work  in  which 
the  weld  to  be  executed  requires  several  hours  with- 
out interruption,  then  lightness  becomes  an  important 
quality  of  the  torch. 

Management. — The  management  and  regulation 
should  be  considered  in  the  light  of  whether  the  torch 
is  to  be  used  by  experts  or  inexperienced  men.  All 
the  different  points  heretofore  enumerated  should 
receive  consideration  owing  to  the  fact  that  types 
approved  in  certain  cases  would  be  rejected  in  others. 
If  search  is  made  for  the  exact  motives  back  of  these 
rejections,  it  will  be  found  that  the  questions  of  form, 
weight,  solidity,  etc.,  have  been  largely  responsible. 

Needless  to  say,  all  torches  are  not  equally  well 
constructed  and  regulated.  The  striking  back  of  the 
flame  into  the  mixing  chamber,  notably  upon  the 
nozzle  becoming  hot,  is  a  serious  defect  because  in 
order  to  avoid  it,  the  welder  increases  the  oxygen 
pressure.  It  is  therefore  an  important  quality  of  a 
blowpipe  not  to  fire  back  or  to  light  the  interior,  even 
after  prolonged  working. 

To  show  that  the  consumption  of  the  oxygen  in  pro- 
portion to  that  of  the  acetylene,  is  a  point  of  consider- 
able importance  both  from  the  point  of  view  of  econ- 
omy and  the  execution  of  good  welds,  take,  for  ex- 
ample, the  case  of  the  small  workshop  using  auto- 
genous welding  on  a  moderate  scale,  say,  2100  cubic 
feet  of  oxygen  per  month.  Suppose  a  bad  blowpipe  is 


CHARACTERISTICS  OF  WELDING  TORCHES  105 

used  requiring  1.8  volumes  of  oxygen  for  1  volume 
of  acetylene,  as  is  frequently  the  case.  As  the  propor- 
tion of  consumption  of  oxygen  in  good  blowpipes  only 
attains  1.2,  the  oxygen  that  should  be  used  under 

these  conditions  is ^— — —  =  1400  cubic  feet.    The 

l.o 

loss  is  therefore  700  cubic  feet,  representing  a  loss  of 
practically  $25.00  per  month  and  $300.00  per  year, 
which  can  be  easily  saved  by  using  a  good  blowpipe. 
Moreover,  in  addition  to  this  loss,  the  excess  of  oxygen 
gives  rise  to  bad  welding. 

This  illustrates  the  importance,  from  economical 
considerations,  of  inquiring  as  to  the  relative  propor- 
tions of  oxygen  and  acetylene,  seeing  that  excess  of 
oxygen  brings  about  bad  welds.  This  factor  is  more 
important  than  the  economy  of  the  gas. 

Therefore  in  choosing  a  blowpipe  system  from  the 
point  of  view  of  the  consumption  of  oxygen,  as  ex- 
plained previously,  one  should  stipulate  a  guarantee 
from  the  constructors;  for  example,  the  maximum 
proportion  is  1.3,  using  the  pressure  of  oxygen  indi- 
cated. This  would  be  quite  sufficient  for  normal  con- 
ditions of  working  of  blowpipes. 

Maintenance  of  Torches. — This  consists  in  keeping 
in  order  the  cocks  and  the  joints  of  the  movable  pieces 
and  the  careful  cleaning  of  the  nozzle  and  tips  from 
time  to  time. 

This  last  operation  is  very  delicate.  In  fact,  one 
must  take  care  not  to  enlarge  the  orifice  of  the  nozzle, 
especially  in  the  blowpipes  for  low  pressure,  because 
the  slightest  change  in  section  produces  derangement. 

It  is  understood  that  for  the  same  blowpipe  the 
section  of  the  nozzle  corresponds  to  a  determined  flow 
of  oxygen,  but  the  orifice  for  the  flowing  of  the  oxygen 


106  OXY-ACETYLENE  WELDING  AND  CUTTING 

(the  injector)  remains  unchanged,  and  any  increase 
of  the  nozzle  opening  brings  about  a  decrease  of 
velocity  at  the  exit,  which  provokes  a  return  of  the 
flame  into  the  interior  of  the  blowpipe. 

The  crusting  of  the  nozzle  by  the  oxides  or  particles 
of  metal  produces  the  following  result:  the  delivery 
of  oxygen  being  invariable  and  escaping  under  a 
greater  pressure  than  the  acetylene,  the  flame  becomes 
oxodizing.  When  the  hole  through  the  nozzle  becomes 
too  small,  it  is  the  stronger  one,  viz.,  the  oxygen,  that 


Figure    45. — The   Scraping   of   the   Nozzle   Should   Not   Be   Done 
with  a  Tool  which  Might  Enlarge  the  Nozzle 

gets  through  in  preference  to  the  acetylene.  It  is 
therefore  necessary  to  watch  that  the  nozzle  does  not 
become  encrusted,  but  it  is  still  more  important  not  to 
enlarge  it  during  cleaning. 

The  decrusting  of  the  nozzle  should  be  done  by 
means  of  brass  wire,  excluding  all  tools  such  as  files, 
and  especially  such  remedies  as  rubbing  the  end  of 
the  nozzle  on  the  bricks  of  the  welding  table  or  on 
metal.  Any  widening  of  the  nozzle  or  increase  of  the 
exit  passage  will  produce  derangement  of  the  torch. 
In  some  cases  particles  of  dust  are  carried  into  the 
interior  of  the  torch,  causing  a  partial  obstruction. 


CHARACTERISTICS. OF  WELDING  TORCHES  107 

The  working  becomes  affected  owing  to  the  difficulty 
of  passage  for  the  gas. 

Some  types  contain  a  metal  curtain  which  is  sup- 
posed to  keep  back  the  dust,  but  this  filter  tends  to 
become  an  obstruction  itself  in  time,  so  the  result  is 
the  same.  The  remedy  for  this  condition  is  to  take 
off  the  tubing  and  connect  the  nozzle  of  the  torch 
directly  to  the  oxygen  cylinder  through  tubing,  then 


Figure  46. — Cleaning  the  Blowpipe  by  Means  of  Oxygen 
Under  Pressure 

raise  the  pressure  of  the  gas  by  means  of  the  reducing 
valve  to  about  10  Ibs.,  and  thus  send  the  gas  through 
the  torch  in  an  opposite  direction  to  its  usual  flow. 
The  acetylene  cock  on  the  torch  being  open,  close  the 
hole  at  which  the  oxygen  usually  enters  with  the  finger 
(see  Figure  46)  so  that  the  oxygen,  under  pressure, 
sweeps  the  passages  clean.  By  playing  on  the  open- 
ing with  the  finger  the  cleaning  is  greatly  facilitated. 
The  same  thing  can  be  done  with  the  oxygen  passages, 
although  the  obstruction  of  this  tube  and  the  injector 
is  very  rare. 

If  in  the  course  of  the  work  it  is  desired  to  cool  a 
torch  which  back-fires  on  account  of  too  great  heating, 
care  should  be  taken  not  to  close  completely  the  oxy- 


108  OXY-ACETYLENE  WELDING  AND  CUTTING 

gen  supply,  but  allow  it  to  flow  sufficiently  to  prevent 
the  entrance  of  water  into  the  orifice  of  the  nozzle. 
Great  care  should  also  be  exercised  to  prevent  grease 
or  oil  from  getting  into  the  interior  of  the  torch, 
especially  the  oxygen  tube,  or  the  mixing  chamber  for 
the  oxygen  and  acetylene. 

No  oiling  is  necessary,  as  any  form  of  oil  or  grease 
will  be  oxidized  by  the  oxygen  gas  and  will  cause 
gumming  and  sticking  of  the  valves.  Another  thing 
to  be  avoided  as  much  as  possible  is  the  taking  of  the 
torch  to  pieces,  because  in  reassembling  it  generally 
requires  adjustment  and  regulation  which  is  the  work 
of  specialists.  In  cases  of  bad  working  and  the  impos- 
sibility of  the  repair  being  made  by  methods  already 
indicated,  the  best  procedure,  and  usually  the  most 
economical,  is  a  speedy  return  of  the  instrument  to  its 
makers. 

Torches  should  be  treated  as  instruments  of  pre- 
cision, ranged  in  good  order,  polished  and  ready  for 
use. 


CHAPTER  VIII 

WELDING    INSTALLATIONS 

An  autogenous  welding  installation,  especially  one 
using  acetylene  at  low  pressure,  comprises  many  other 
details  and  accessories  in  addition  to  acetylene  gen- 
erators, cylinders  of  oxygen  and  torches.  There  are 
the  mains  and  service  pipes  from  the  generator  to  the 
welding  place ;  the  safety  valve,  which  is  indispensable 
to  installations  using  low  or  medium  pressure  acet- 
ylene ;  the  oxygen  reducing  valves ;  the  flexible  tubes 
carrying  the  gases  to  the  torches;  the  welding  tables 
and  their  accessories ;  and  lastly,  the  special  arrange- 
ments for  certain  kinds  of  work.  The  security  and 
successful  working  of  a  welding  installation  depends 
in  a  large  measure  on  a  thorough  understanding  of 
these  various  details. 

Acetylene  Piping. — In  the  majority  of  autogenous 
welding  installations  now  in  operation,  the  pipes  which 
convey  the  acetylene  from  the  generator  to  the  weld- 
ing place  are  of  too  small  section  for  the  good  working 
of  the  torches  with  large  delivery.  The  result  of  this 
is  a  serious  loss  of  pressure,  thus  tending  to  prevent 
the  acetylene  arriving  in  sufficient  quantity  and  under 
normal  pressure  at  the  torch.  The  welder  is  thereby 
forced  to  increase  the  pressure  of  the  oxygen  in  order 
to  draw  enough  acetylene  and  often  it  will  happen 
that  air  is  drawn  in  through  the  discharge  tube  of 
the  hydraulic  valve.  To  obviate  this  difficulty,  the 
cross  section  of  the  acetylene  pipe  should  be  in  rela- 
tion to  the  delivery  and  should  provide  for  the  maxi- 

109 


110  OXY-ACETYLENE  WELDING  AND  CUTTING 

mum  consumption  for  the  largest  torch  that  is  to  be 
used. 

The  loss  of  pressure  for  a  predetermined  delivery 
depends  not  only  on  the  diameter  of  the  pipe,  but  also 
on  its  length.  In  a  good  system  of  piping,  this  loss 
should  not  exceed  %  inch  of  water.  If  the  gas  leaves 
the  generator  or  purifier  at  a  pressure  of  5  inches  of 
water,  for  example,  the  pressure  on  entering  the 
hydraulic  valve  should  be  4%  inches  even  during  the 
working  of  the  largest  and  most  powerful  torch.  This 
favorable  result  is,  however,  rarely  obtained,  owing  to 
the  use  of  too  small  a  pipe. 

Following  is  an  example  of  what  is  liable  to  occur 
with  a  pipe  having  an  interior  diameter  of  %  inch. 
If  the  piping  is  35  feet  long,  the  delivery  can  attain 
81  cubic  feet  per  hour  without  the  loss  of  pressure 
exceeding  %  inch  of  water ;  but  for  50  feet  it  falls  to 
67  cubic  feet;  then  for  100  feet  it  is  48  cubic  feet;  for 
165  feet  it  is  35  cubic  feet,  and  for  330  feet  it  is  26 
cubic  feet. 

If  a  welding  installation  should  deliver  50  cubic  feet 
of  acetylene  per  hour,  a  pipe  of  %-inch  diameter, 
which  is  sufficient  for  a  length  of  80  feet,  should  be 
increased  to  ^  inch  for  165  feet,  and  to  ^f  inch  for 
260  feet. 

The  above  examples  are  given  to  show  that  the 
diameter  of  the  pipe  should  depend,  not  only  on  the 
maximum  delivery  that  may  be  required  from  an 
installation,  but  also  upon  the  length  of  the  piping. 

Table  four  will  be  of  assistance  in  finding  the 
necessary  diameter  of  pipe  according  to  the  length 
and  maximum  hourly  delivery.  As  the  figures  given 
in  the  table  are  obtained  by  theoretical  calculation,  it 
will  be  necessary  in  practice  to  take  into  account 


WELDING  INSTALLATIONS 


111 


unevenness  of  the  pipes,  leaky  joints,  etc.,  and  to 
allow  a  slightly  greater  diameter  than  that  which 
corresponds  to  the  immediate  future  maximum  con- 
sumption of  the  installation. 

TABLE  IV. 

NUMBER    OF    CUBIC    FEET    OF    ACETYLENE    FLOWING    PER 

HOUR  IN  A  GIVEN  DIAMETER  AND  LENGTH  OF 

PIPING  FOR  A  LOSS  OF  0.4  INCH  OF 

WATER  PRESSURE 


If- 

Diameter  of  Piping  in  Inches. 

C'ft£ 

ii 

» 

% 

ii 

il 

1 

1ft 

1% 

cub. 
ft. 

cub. 
ft. 

cub. 
ft. 

cub. 
ft. 

cub. 
ft. 

cub. 
ft. 

cub. 
ft. 

cub. 
ft. 

35 

27.6 

53 

84 

Ill 

152 

50 

20.5 

40 

67 

92 

119 

65 

18.4 

35 

58 

79 

103 

179 

80 

16.3 

SI 

52 

68 

91 

160 

100 

14.8 

28 

48 

65 

83 

146 

250 

130 

12.7 

25 

41 

56 

73 

126 

218 

165 

11.3 

22 

37 

50 

64 

112 

193 

262 

200 

10.6 

20 

34 

46 

5) 

104 

177 

240 

230 

9.9 

18 

31 

41 

55 

95 

102 

222 

260 

9.2 

17.5 

29 

39 

51 

90 

153 

201 

215 

8.5 

16.4 

27 

37 

48 

84 

143 

195 

330 

7.8 

15.5 

26 

35 

45 

80 

125 

185 

Connections. — The  unions,  joints  or  cocks  should 
have  an  area  of  cross  section  equal  to,  or  very  little 
less  than,  that  of  the  piping;  this  from  the  generator 
to  the  safety  valve.  A  piping  of  appropriate  diameter 
becomes  useless  if  the  gas  is  throttled  at  one  or  more 
points. 

In  the  majority  of  workshops  using  autogenous 
welding,  the  acetylene  piping  consists  of  iron  tubes 


112  OXY-ACETYLENE  WELDING  AND  CUTTING 

joined  with  unions,  fixed  to  a  wall  or  suspended.  It  is 
advisable  to  use  galvanized  piping,  for  the  reason  that 
with  plain  iron  the  gas,  always  a  little  moist,  forms 
more  or  less  rust,  which  comes  off  in  a  powder  and 
may  accumulate  in  certain  parts. 

Where  the  piping  follows  walls  and  there  is  no 
danger  of  crushing,  the  use  of  lead  pipe  is  preferable 
for  the  following  reasons:  oxidation  need  not  be 
feared ;  there  is  less  danger  of  leakage ;  new  branches 
can  be  connected  without  difficulty,  and  in  case  of 
removal  due  to  increase  of  welding  capacity,  for  ex- 
ample, the  metal  practically  preserves  its  value. 

Iron  pipes,  however,  possess  the  advantage  of  being 
more  rigid  and  are  not  so  liable  to  be  affected  by 
shocks.  Pipes  or  tubes  of  copper  should  not  be  used, 
especially  if  the  acetylene  has  not  been  purified,  owing 
to  the  danger  of  formation  of  acetylene  of  copper, 
which  is  spontaneously  explosive.  Brass  is  not  sub- 
ject to  this  disadvantage,  but  its  use  is  hardly  justi- 
fiable except  for  unions  and  cocks  in  the  piping.  The 
cocks  should  be  carefully  made  and  for  large  systems, 
cast  iron  cocks  may  be  used  with  advantage. 

The  piping  should  be  absolutely  gas-tight  and  be 
tested  after  erection,  and  the  tightness  verified  from 
time  to  time.  The  use  of  a  flame  in  searching  for  leaks 
is  dangerous.  In  the  absence  of  a  compression  pump, 
and  location  by  the  hissing  sound,  the  odor  of  the  gas 
or  the  use  of  soap  and  water  may  be  depended  upon. 

Safety  Valves. — Mixtures  of  oxygen  and  combus- 
tible gases  being  explosive  in  a  high  degree,  all  pre- 
cautions should  be  taken  to  prevent  their  formation, 
especially  when  their  ignition  is  produced  very  easily, 
as  by  the  passage  of  the  flame  through  wire  gauze, 
small  openings,  etc.  When  acetylene  is  used  under 


WELDING  INSTALLATIONS 


113 


pressure  lower  than  that  of  the  oxygen,  which  is  the 
case  in  all  installations  comprising  an  acetylene  gen- 
erator, the  oxygen  can  return  in  the  acetylene  tubes 
and  piping  and  mix  with  the  acetylene,  even  as  far 
back  as  the  generator.  This  is  the  case  especially  when 
there  is  a  total  or  partial  obstruction  of  the  nozzle  of 
the  torch,  and  it  is  therefore  indispensable  to  place 
in  the  acetylene  piping,  before  the  flexible  tubes  reach 


Figure  47. — Hydraulic  Safety  Valve  During  the  Normal  Working 
of  the  Blowpipe 

the  torch,  a  perfect  device,  capable  of  immediately 
arresting  any  return  of  the  oxygen  in  the  acetylene 
piping. 

This  is  the  very  important  function  of  the  safety 
valve.  It  is  not  a  question  of  avoiding  the  return  of 
the  flame,  but  to  prevent  the  mixture  of  the  two  gases 
which  would  be  explosive  by  the  return  of  the  flame 
or  from  any  other  cause.  Another  function  of  the 
safety  valve  is  to  direct  any  oxygen  which  returns  in 
the  direction  of  the  acetylene,  into  the  open  air  and 


114 


OXY-ACETYLENE  WELDING  AND  CUTTING 


thus  prevent  its  flowing  further  into  the  piping  for 
this  gas.  Figures  47  and  48  are  sectional  elevations 
illustrating  the  action  of  the  hydraulic  safety  valve. 

The  essential  method  of  working  is  for  the  acetylene 
to  bubble  through  a  small  height  of  water,  but  never- 
theless sufficient  for  covering  the  tube  leading  to  the 
exterior,  this  being  between  the  surface  of  the  water 


Figure  48.— The  Hydraulic  Valve  at  the  Moment  of  the  Return 
of  the  Oxygen 

and  the  level  of  the  escaping  acetylene.  If  there  is  a 
return  of  oxygen,  the  pressure  exerted  on  the  surface 
of  the  water  makes  the  liquid  rise  in  the  tube  open  to 
the  air,  forces  it,  if  necessary,  into  the  exterior,  in  such 
a  way  that  this  same  tube  eventually  discharges  the 
oxygen,  the  acetylene  orifice  meanwhile  being  pro- 
tected by  a  seal  of  water. 

The  principle  is  not  all  that  is  required.  It  is  fur- 
ther necessary  that  the  construction  should  have  been 
studied,  and,  in  practice,  one  meets  few  hydraulic 


WELDING  INSTALLATIONS  115 

valves  established  under  normal  conditions  of  safety 
and  good  working. 

It  is  necessary,  first  of  all,  to  avoid  too  large  a  gas 
capacity  in  the  valve,  because,  in  case  of  the  return 
of  the  oxygen,  and  subsequent  ignition,  the  explosion 
may  be  violent  enough  to  break  the  valve  and  its  parts. 
On  the  other  hand,  the  diameter  of  the  body  should  be 
sufficient  that  the  level  of  the  water  will  remain  fairly 
constant,  and  the  height  great  enough  to  avoid  carry- 
ing drops  of  water  to  the  outlet  for  the  acetylene,  and 
thence  into  the  nozzle. 

The  large  central  tube  leading  the  acetylene  into  the 
hydraulic  valve  should  be  of  suitable  cross  section  for 
the  maximum  delivery  of  the  torch  in  order  to  avoid 
all  loss  of  pressure.  A  tube  whose  diameter  is  too 
small  is  liable,  when  using  a  large  torch,  to  cause  a 
depression  in  the  valve,  which  may  produce  a  suction 
of  air  through  the  open  tube.  In  ordinary  welding 
practice  the  tube  should  have  a  minimum  diameter  of 
1/2  to  %  inch. 

The  bottom  of  the  tube  leading  the  acetylene  to  the 
water  in  the  valve,  should  have  a  larger  cross  section, 
as  shown  in  figures  47  and  48,  and  be  notched  or 
pierced  with  small  holes  in  order  to  avoid  the  pulsa- 
tion of  the  gas  by  the  ascension  of  large  bubbles.  The 
height  of  the  water  between  the  acetylene  exit  holes 
and  the  surface  of  the  liquid,  as  given  by  the  level 
cock,  should  be  sufficient  to  allow  the  placing  of  the 
tube  leading  to  the  atmosphere  without  its  being  un- 
covered if  the  water  level  should  be  slightly  lowered, 
and  without  the  exit  holes  being  uncovered  in  the 
event  of  the  return  of  the  oxygen.  This  takes  into 
account  the  difference  of  the  level  which  may  follow 
the  rising  of  the  water  under  the  effect  of  pressure  in 


116  OXY-ACETYLENE  WELDING  AND  CUTTING 

the  tube  in  which  the  gas  arrives  or  in  the  one  open  to 
the  atmosphere. 

A  depth  of  water  ranging  from  1%  to  2  inches  is 
usually  sufficient.  The  tube  leading  to  the  outside 
should  be  located  half  way  between  the  level  of  the 
water,  as  fixed  by  the  cock,  and  the  orifice,  or  the  holes 
from  which  the  acetylene  bubbles.  This  tube  should 
be  arranged  in  such  a  manner  that  the  bubbles  of  gas 
passing  through  the  water  will  not  enter  it  under  ordi- 
nary working  conditions.  The  cross  section  should  be 
as  small  as  possible  to  prevent  the  lowering  in  the 
valve  under  the  pressure  of  the  acetylene,  but  large 
enough  to  allow  for  the  rapid  discharge  of  the  water, 
or  gas,  in  case  of  the  return  of  the  oxygen. 

A  diameter  of  %  inch  should  be  sufficient  in  ordi- 
nary cases.  The  height  of  this  outside  tube  depends 
essentially  on  the  pressure  of  the  acetylene,  since  the 
water  rises  in  this  tube  as  the  pressure  of  the  gas  is 
increased.  The  height  should  be  related  to  the  change 
of  level  of  the  water  in  the  valve,  and  should  therefore 
be  greater  than  that  of  a  column  of  water  correspond- 
ing to  the  greatest  possible  pressure  that  may  be  given 
by  the  acetylene  generator. 

Hydraulic  valves  are  usually  made  for  acetylene 
pressures  varying  from  4  to  5  inches  of  water,  and  the 
outside  tube  always  has  a  height  of  8  to  12  inches. 
For  higher  pressures  it  is  necessary  to  increase  this 
height,  and  to  modify  the  valve  in  such  a  manner  that 
the  rising  of  the  water  in  the  tube  should  not  lower  too 
much  the  level  in  the  valve. 

The  outside  tube  terminates  in  a  chamber  or  funnel 
which  serves  for  filling  the  valve  with  water.  This  is 
covered  by  a  lid,  which  prevents  the  projection  of 
water  into  the  open  in  case  of  return. 


WELDING  INSTALLATIONS 


117 


Figure    49. — Design    of    Hydraulic    Valve 


118  OXY- ACETYLENE  WELDING  AND  CUTTING 

The  valves  should  be  made  of  plate  or  strong  tubes. 
"Where  possible,  the  bottom  should  be  jointed  and  not 
welded,  so  that  in  case  of  ignition  after  the  return  of 
the  oxygen,  the  deflagration,  if  very  strong,  breaks 
the  joint. 

Figure  49  is  a  dimensioned  drawing  of  the  principle 
of  the  hydraulic  valve.  A  good  hydraulic  valve  does 
not  get  out  of  order.  It  is  only  necessary  to  verify  the 
level  of  the  water  each  day  by  means  of  the  cock  for 
this '  purpose.  It  is  preferable  that  this  operation 
should  be  done  with  the  valve  under  working  pressure, 
that  is,  with  the  acetylene  arrival  tube  open.  It  is 
advisable  from  time  to  time  to  empty  the  water,  which 
gets  dirty  and  contains  sediment  capable  of  obstruct- 
ing, more  or  less,  the  orifices  for  exit  of  the  gas.  The 
bottom,  joined  simply  and  hermetically  sealed,  makes 
this  operation  very  easy,  and  enables  one  to  examine 
at  the  same  time  the  various  details  and  see  if  these 
are  in  a  good  condition. 

In  order  to  avoid  badly  designed  or  badly  con- 
structed valves,  so  frequently  met  in  practice,  one 
should  see  that  the  safety  arrangements  satisfy  the 
conditions  we  have  just  given. 

The  efficacy  of  such  an  apparatus  should  be  abso- 
lute, and  one  should  rigorously  reject  all  arrange- 
ments based  on  the  movement  of  a  valve  which 
obstructs  the  drawing  of  the  acetylene  when  the  pres- 
sure is  reversed.  Not  only  may  such  an  arrangement 
not  work,  but  its  tightness  is  uncertain,  even  when,  by 
a  mechanical  artifice,  the  oxygen  may  be  discharged 
into  the  open. 

One  should  therefore  use  the  hydraulic  safety  valve, 
in  which  from  a  layer  of  water  emerge  two  tubes,  one 
for  the  entry  of  the  gas,  the  other  open  to  the  exterior, 


WELDING  INSTALLATIONS  119 

placed  at  different  heights,  constituting  an  absolute 
barrier  to  all  return  of  the  oxygen  in  the  acetylene 
piping,  without  any  possibility  whatever  of  failure. 

Oxygen  Reducing  Valves. — The  storage  of  oxygen 
in  steel  cylinders  under  high  pressure  has  been  dis- 
cussed in  another  chapter,  and  it  has  also  been  seen 
that  the  torches  receive  the  gas  under  a  much  lower 
pressure,  generally  from  6  to  28  Ibs.  per  square  inch. 
The  pressure  of  the  oxygen  must  therefore  be  reduced 
and,  at  the  same  time,  regulated  in  such  a  manner  that 
it  remains  automatically  constant  no  matter  what  the 
pressure  may  be  in  the  oxygen  cylinder.  This  result 
is  obtained  by  using  special  apparatus  adapted  to  the 
oxygen  cylinders,  called  reducing  valves  or  pressure 
regulators. 

It  is  absolutely  necessary  to  use  an  oxygen  reducing 
valve  in  autogenous  welding  or  the  cutting  of  metals. 
In  fact  it  is  important  to  use  the  oxygen  under  a  pres- 
sure automatically  regulated  and  to  know  at  any 
moment  the  value  of  this  pressure.  Eeliable  reducing 
valves  are  delicate  instruments,  but  with  correct  ideas 
and  proper  care,  it  is  easy  to  keep  them  in  perfect 
working  condition.  There  are  a  number  of  reliable 
types,  which,  while  they  may  differ  considerably  in 
construction,  all  work  on  the  same  principle. 

Referring  to  Figure  50,  the  oxygen  arrives  from  the 
cylinder  by  way  of  a  straight  passage,  passes  through 
a  filter  designed  to  retain  any  dust,  transmits  its  pres- 
sure to  a  gauge  placed  in  connection  with  the  passage, 
and  which  indicates  the  pressure  in  the  cylinder  at 
any  moment.  From  the  filter  the  oxygen  passes  into 
the  principal  part  of  the  instrument,  which  is  the  auto- 
matic pressure  reducer.  The  reducing  valve  comprises 
a  mechanism  for  opening  and  closing  the  gas  passage 


120 


OXY-ACETYLENE  WELDING  AND  CUTTING 


by  an  ebonite  seating  controlled  by  a  lever,  the  lever 
in  turn  being  controlled  by  a  diaphragm  and  the  dia- 
phragm being  more  or  less  deflected  by  the  pressure. 

A  spring  arrangement,  regulated  from  the  exterior, 
opposes  the  deflection  of  the  diaphragm,  and  serves 
to  regulate  the  pressure  to  that  required,  this  pressure 
being  indicated  by  a  second  gauge,  termed  the  reducer 


Figure  50. — Section  of  Reducing-  Valve,  Showing-  Details 

gauge,  which  the  welder  consults  in  regulating  the 
flame. 

The  working  of  the  apparatus  is  as  follows :  The 
gas  presses  against  the  elastic  diaphragm  until  the 
required  and  predetermined  pressure  is  reached ;  the 
diaphragm  is  then  deflected  and  moves  the  lever  which 
controls  the  passage  of  the  gas.  If  the  pressure  tends 
to  fall,  the  diaphragm  ceases  to  hold  the  lever,  the 
small  valve  opening  is  opened  and  so  on.  In  this 
manner  an  equilibrium  is  obtained  which  gives  a 
constant  pressure  no  matter  what  the  delivery  or  what 
the  pressure  of  the  gas  in  the  cylinder  may  be. 

The  regulation,  as  has  already  been  explained,  is 


WELDING  INSTALLATIONS  121 


Figure  51.— Portable  Welding  Outfit 


122  OXY-ACETYLENE  WELDING  AND  CUTTING 

controlled  from  the  exterior  by  pressure  on  the  dia- 
phragm in  an  opposite  direction  to  that  of  the  gas  in 
such  a  manner  that  oxygen  may  be  obtained  under 
any  desired  pressure.  A  valve  may  communicate  with 
the  atmosphere  from  the  reducing  chamber,  its 
function  being  to  allow  escape  of  the  gas  should  bad 
working  of  the  ebonite  valve  or  other  derangement 
allow  the  pressure  to  become  too  high. 

Acetylene  reducing  valves  are  attached  to  the  acet- 
ylene tanks  for  the  purpose  of  reducing  and  control- 
ling the  pressure  of  the  gas  for  welding.  These  act 
on  the  same  principle  as  the  oxygen  valves,  the  only 
difference  being  in  the  material  used  in  some  of  the 
interior  parts. 

Figure  51  shows  a  complete  portable  welding  outfit. 
The  reducing  valves  are  shown  attached  to  both  the 
oxygen  and  acetylene  tanks.  Oxygen  reducing  valves 
are  usually  equipped  with  two  gauges,  one  being  for 
high  pressure  and  showing  the  tank  pressure.  Figure 
52  is  an  enlarged  view  of  a  reducing  valve  equipped 
with  both  high  and  low  pressure  gauges,  the  tank 
gauge  reading  to  3000  Ibs.  and  the  torch  valve  to  30 
Ibs. 

Reducing  valves  are  secured  to  the  cylinders  by 
means  of  a  union  screwed  into  the  cylinder  valve  open- 
ing. Tightness  is  assured  by  simply  tightening  the 
ground  faces.  The  operation  of  connecting  is  as  fol- 
lows : — 

(1)  Screw  the  movable  part  of  the  union  as  far 
back  as  possible  so  that  the  part  fitted  into  the  valve 
socket  of  the  cylinder  is  left  free. 

(2)  Place  the  reducing  valve  as  shown  in  Figure  53 
and  enter  the  union  into  the  valve  socket.    Now  turn 
the  nut  until  tight. 


WELDING  INSTALLATIONS 


123 


(3)  Unscrew  the  nut  slightly  so  as  to  be  able  to  tilt 
the  faces  of  the  gauges  a  little  forward  or  to  one  side, 
according  to  the  type,  then  fasten  all  together  with 
the  hands  and  lastly  complete  the  fastening  with  the 
aid  of  the  reducing  valve  grasped  in  both  hands  and 


Figure   52. — Reducing:  Valve  with   High   Pressure  Gauge 

turned  with  reasonable  force.  This  should  place  the 
gauges  where  they  can  be  easily  seen.  If  the  joint  is 
not  perfectly  gas  tight  it  may  be  further  tightened  by 
the  union,  but  too  much  force  should  not  be  used. 

Figure  54  shows  the  proper  method  of  starting  the 
flow  of  oxygen.    The  oxygen  tank  valve  should  always 


124  OXY-ACETYLENE  WELDING  AND  CUTTING 

be  opened  as  slowly  as  possible  and  the  reducing 
valve  should  previously  have  had  its  regulating  screw 
turned  out  until  entirely  free.  The  outlets  for  the  gas 
and  the  cocks  should  all  be  open  through  to  the  nozzle. 
In  this  manner,  heating  by  quick  compression  is 
practically  avoided.  These  instructions  are  important 
for  the  safety  of  the  welder  and  the  preservation  of 
the  apparatus  in  a  good  working  state,  because  sudden 
gusts  of  pressure  on  the  diaphragm  of  the  reducer  pro- 
duce derangement  and  quickly  put  it  out  of  order. 


Figure  53. — Fixing  the  Reducing-  Valve  on  the  Oxygen  Cylinder 

After  opening  the  cylinder  it  is  only  necessary  to 
slowly  screw  up  the  regulating  screw  to  obtain  the 
required  pressure.  The  outlet  cock  on  the  reducing 
valve  should  be  opened  wide,  and  should  not  be  used 
for  regulating  the  gas  to  the  blowpipe. 

Flexible  Tubes  and  Connectors. — For  the  operation 
of  the  torch,  the  acetylene  and  oxygen  are  delivered 
to  it  through  separate  tubes,  one  coming  from  the 
hydraulic  valve  (or  cylinder  of  acetylene  if  one  is 
used),  and  the  other  from  the  oxygen  reducing  valve. 
These  tubes  may  be  of  varying  length,  according  to 
the  degree  of  movement  the  welder  will  be  required  to 


WELDING  INSTALLATIONS  125 

make.  In  many  localities  there  is  a  certain  minimum 
length  of  tubing  and  minimum  distance  that  is  allowed 
between  the  tanks  and  torch-.  This  varies  from  25  to 
50  feet.  The  flexible  tubes  are  made  of  rubber, 
covered  with  canvas,  or  into  which  canvas  has  been 
woven.  They  should  be  strong  enough  to  resist  sev- 
eral times  the  highest  pressure  used  and  not  easily 
damaged  by  chafing,  knocks,  burns,  etc. 

This  valve 
should  be 
open. 


Figure   54. — Opening-   Valve   in   the   Oxygen   Cylinder 

In  some  places  the  regulations  require  that  the 
tubes  should  be  protected  by  an  incombustible  cover- 
ing, and  the  tendency  has  been  to  use  flexible  metallic 
tubes  or  spiral  tubes,  sheathed  with  metal  wire,  etc- 
These  types  of  flexible  tubes  are  not  to  be  recom- 
mended, because  they  deteriorate  very  easily,  especially 
with  sudden  bends,  or  burns,  such  injuries  not  being 
easily  noticed,  which  increases  the  danger. 

The  use  of  tubes  of  different  diameters  or  differ- 


126  OXY- ACETYJLENEI  WELDING  AND  CUTTING 

ent  colors  according  to  whether  they  carry  oxygen  or 
acetylene  has  been  recommended. 

There  should  be  standard  connectors  on  the  torch, 
the  hydraulic  valve  and  the  reducing  valves.  This 
standardization  is  important  because  the  details  that 
go  to  make  up  a  welding  installation  are  frequently 
not  of  the  same  design  or  make,  and  when  it  is  neces- 
sary to  replace  details  with  others  having  different 
size  connectors,  it  becomes  inconvenient  and  sometimes 
almost  impossible  to  make  good  joints. 


Figure  55. — Standard  Connector 

The  connector  for  the  rubber  tube  should  be  stan- 
dard both  in  form  and  dimensions  and  should  be  the 
same  for  acetylene  and  oxygen.  The  form  and  dimen- 
sions given  by  the  drawing,  Figure  55,  represents  a 
good  type.  The  interchangeability  of  the  connector 
for  the  rubber  and  the  thread  of  its  union  could 
remain  optional.  This  standard  connector  has  been 
adopted  by  the  majority  of  the  makers  of  torches 
and  reducing  valves  and  should  be  used  for  installa- 
tions using  75  to  100  cubic  feet  of  acetylene  per  hour. 

The  bore  of  connectors  should  be  as  large  as  pos- 
sible, depending  of  course  on  the  outside  dimensions. 
The  flexible  tubes  should  have  a  cross  section  appropri- 
ate to  the  standard  connector  so  that  it  can  be  simply 
pushed  on  without  fear  of  splitting. 

Some  firms  supply  a  fitting  which  constitutes  a  com~ 
plete  fastening  attached  to  the  rubber,  which  is  cov- 


WELDING  INSTALLATIONS  127 

ered  by  a  wire  network,  and  which  is  attached  by 
means  of  a  wing-nut. 

The  flexible  tubes  do  not  require  any  particular  care 
beyond  the  prevention  of  burning,  tearing,  wear  by 
friction,  etc. ;  there  should  be  no  chafing  in  the  interior, 
especially  where  it  fits  on  the  connectors,  as  the  par- 
ticles which  become  detached  can  obstruct  the  passages 
and  organs  of  the  blowpipe.  Never  grease  the  rubber 
or  the  connectors  for  the  gases  in  order  to  make  them 


Figure    56. — Table    for    Welding:    Small    Articles 

fit  each  other  easily;  if  necessary,  they  should  be 
moistened  writh-  water. 

Welding  Table. — When  the  work  to  be  welded  is 
not  too  large  it  is  best  performed  on  a  welding  table, 
which  should  be  made  entirely  of  metal,  except  the 
covering,  which  should  be  of  fire-bricks  simply  placed 
one  against  the  other.  Figure  56  shows  one  of  the 
simplest  arrangements,  consisting  of  T3g-inch  iron 
plates  placed  across  two  iron  trestles  and  covered 
with  fire  brick. 

The  standard  type  of  welding  table  is  made  in  one 
or  two  hours  by  autogenous  welding.  Use  stock  size 
of  angle  iron  2*4  inches  x  21/4  inches  x  %  inch.  First 


128  OXY-ACETYLENE  WELDING  AND  CUTTING 

cut  (with  the  blowpipe)  4  lengths  of  2%  feet  for  the 
legs  of  the  table,  then  4  lengths  of  3%  feet  for  the 
long  side,  and  four  lengths  of  21/4  to  2y2  feet  for  the 
short  side,  the  tables  generally  being  rectangular. 


Figure   57. — Welding-  Table  of  Angle  Iron  Entirely   Constructed 
with  the  Blowpipe 

The  joining  of  the  twelve  pieces  of  angle  iron  by  auto- 
genous welding  is  shown  in  Figures  58,  59  and  60. 
First  weld  the  two  frames,  which  must  be  cut  at  the 
ends  to  angles  of  45°  in  order  to  fit  the  pieces  to- 


Figure    58. — Detail    of    Execution    of    Frames 

gether.  Next  joint  the  two  frames  to  the  legs,  one  at 
the  top  and  the  other  about  two-thirds  down,  welding 
the  first  on  the  top  and  sides  and  the  second  simply 
on  the  sides.  Next  fix  a  plate  in  each  of  the  two 
frames,  covering  the  top  one  with  fire  bricks  placed 


WELDING  INSTALLATIONS 


129 


side  by  side,  (see  Figure  57).    The  lower  shelf  serves 
as  a  place  for  tools,  welding  rod,  etc. 

Of  course  the  dimensions  here  given  can  be  varied 


Figure  59.— Welding  of  the  Frames  of  the  Legs 

to  suit  the  requirements  of  the  shop,  for  instance,  the 
tables  can  be  higher  or  lower,  or  much  larger  or  longer 
as  conditions  and  the  nature  of  the  case  may  demand. 


Figure  60. — Table  Entirely  Welded 

Other  types  can  be  studied  and  constructed,  which 
may  suit  the  particular  work  of  the  welder  much 
better  than  the  rectangular  form  illustrated. 

Tables  can  be  made,  similar  to  the  one  shown  in 


130  OXY-ACETYLENE  WELDING  AND  CUTTING 

Figure  61,  in  which  the  top  portion  can  be  raised  as 
required,  inclined  or  turned — movements  which  may 
be  extremely  convenient  for  certain  work.  Tables  can 
also  be  designed  which  contain  a  warming  oven  to 
preheat  the  parts  to  be  worked.  This  may  be  made  so 


Figure  61. — Welding  Table  with  Adjustable  Top 

that  it  can  be  taken  apart  easily  and  used  for  the 
repair  of  small  pieces  of  cast  iron,  bronze,  aluminum 
alloys  and  similar  work  which  require  preliminary 
heating  and  slow  cooling. 

Preparation  of  Welds. — A  weld  well  prepared  is 
half  done,  because  the  facility  of  execution  depends  in 
a  large  measure  on  the  arrangements  made  by  the 
welder  in  the  preparation  of  the  parts  to  be  joined. 
In  detail,  this  preparation  varies  notably  with  the 
nature  of  the  metal,  thickness  of  weld,  and,  above  all, 


WELDING  INSTALLATIONS  131 

the  form  and  position  of  the  parts  to  be  welded ;  but 
it  follows  general  rules  which  serve  to  indicate  the 
methods  to  be  applied  in  each  particular  case. 

Beveling  means  cutting  to  form  an  angle,  or  slope, 
or  chamfer.  Beveling  the  edges  to  be  welded  is  to 
facilitate  the  execution  of  the  work  and  to  make  sure 
of  melting  the  metal  throughout  the  thickness  of  the 


Figure  62. — Beveling  for  Pieces  from    %   inch  to   T35   inch  in 
Thickness,  Angle  of  Bevel,  45° 

weld.  It  offers  equally  the  advantage  of  enlarging 
the  line  of  joining,  that  is  to  say,  it  avoids  the  conse- 
quences of  too  great  a  localization  of  the  defects,  and, 
lastly,  it  allows  the  addition  of  a  much  greater  quan- 
tity of  metal  of  better  quality  and  containing  the  re- 
quired deoxidizing  materials. 

Figures  62  and  63  show  examples  of  beveling  for 


Figure  63. — Beveling  for  Thickness  Exceeding  T3ff  inch,   Angle 
of  Bevel,  90° 

various  thickness  of  welds.  From  %  to  -£$  inch  a 
slightly  open  bevel  is  sufficient,  the  inclined  surfaces 
forming  an  angle  of  45°  for  example.  For  thicknesses 
of  T3F  inch  and  greater,  the  angle  is  increased  to  as 
much  as  90°. 

The  beveling  is  obtained,  according  to  the  case,  by 
chisel,  file,  or  grinding  machine;  the  cutting  should 


132  OXY-ACETYLENE  WELDING  AND  CUTTING 

be  regular,  especially  at  the  bottom,  so  as  not  to  pro- 
duce holes  or  excess  thickness  at  the  bottom  of  the 
bevel. 

Rolled  plates  (tubes,  etc.)  offer,  at  their  junction,  a 
bevel  which  only  requires  retouching.  In  the  joining 
of  angle  irons,  plates  at  angles,  etc.,  the  beveling 
necessary  for  the  good  execution  of  the  weld  is  also 
obtained  without  cutting,  because  the  edges  are  ar- 
ranged so  as  to  practically  form  an  angle  of  90°.  We 
shall  see  later  that  this  method  of  joining  is  not  always 
to  be  recommended. 

The  necessity  for  beveling  exists,  whatever  the  metal 
to  be  welded — steel,  cast  iron,  copper,  aluminum,  etc. 
Separating  the  edges  to  be  welded  will  not  suffice  for 
beveling.  This  practice  should  be  avoided. 

Adjusting. — The  correct  arrangement  and  securing 
of  the  parts  to  be  joined  so  that  during  the  welding 
they  will  remain  perfectly  in  position  is  another  im- 
portant matter  in  the  preparation  and  support  of 
work  to  be  welded.  The  angles  of  the  bevel,  or  the 
edges  to  be  joined  should  be  held  exactly  at  the  same 
level.  In  cases  of  repairs  to  non-malleable  pieces,  as 
for  instance,  toothed  wheels,  parts  of  machines,  etc., 
the  adjustment  before  welding  should -be  very  care- 
fully done.  The  maintaining  in  position  of  the  parts 
on  the  table  or  otherwise  is  obtained  by  means  of 
wedges,  keys,  clamps,  iron  wire,  etc. 


CHAPTER  IX 

PREHEATING   AND   ANNEALING 

All  welding  installations  and  especially  those  con- 
cerned with  the  handling  of  articles  in  cast  iron  or 
aluminum,  should  be  equipped  with  facilities  for  the 
preheating  and  slow  cooling  or  annealing  of  these 
articles.  The  successful  repair  of  cast  iron,  bronze, 
and  alloys  of  aluminum  requires,  previous  to  the 
actual  welding,  careful  preheating  of  the  article,  fol- 
lowed after  the  welding  by  a  very  slow  cooling,  in 
order  to  avoid  the  effects  of  expansion  and  contrac- 
tion. 

Furthermore,  the  annealing  after  welding  tends  to 
remove  internal  strains  and  it  is  always  advisable  to 
do  this  where  there  is  no  special  difficulty  standing 
in  the  way.  Of  course,  the  construction  of  a  pre- 
heating furnace,  may  in  some  cases  be  rather  compli- 
cated owing  to  the  different  sizes  of  articles  to  be 
handled. 

Nevertheless,  in  those  workshops  that  take  orders 
for  the  repair  of  many  articles  of  the  same  kind,  for 
instance,  cylinders  and  gear  cases  of  automobiles,  the 
installation  of  a  permanent  oven  has  great  advantages 
as  viewed  from  the  point  of  economy  in  fuel  and  the 
regularity  of  preheating  and  slow  cooling. 

Figure  64  shows  the  design  of  one  of  these  ovens 
which  may  also  be  arranged  to  serve  the  purposes  of 
a  table  while  doing  the  work.  The  hinered  cover  may 
be  altered  to  accommodate  various  conditions  in  the 
work. 

Precautions  Relative  to  Expansion  and  Contraction. 

133 


134 


OXY-ACETYLENE  WELDING  AND  CUTTING 


— These  phenomena,  in  the  ease  of  autogenous  weld- 
ing, are  liable  to  produce  the  following  defects :  de- 
formation, breaks  or  cracks  and  internal  strains.  If 
the  whole  of  the  piece  to  be  welded  can  be  raised  to 
a  high  heat,  somewhere  near  the  melting  point,  and 
then  uniformly  cooled  after  welding,  no  serious  results 
need  be  feared. 


Figure   64. — Workshop   Oven   for   the  Repairing  and  Welding  of 
Articles  of  Cast  Iron  and  Aluminum 

Castings  should  be  heated  in  a  convenient  manner 
to  a  dull  red  heat,  except  engine  or  pump  cylinders 
[if  cylinders  are  heated  to  a  red  heat  it  is  liable  to. 
warp  them],  and  the  torch  applied  when  it  is  in  this 
condition.  It  is  important  to  remember  that  this 
sort  of  work  should  be  done  rather  slowly.  If  the 
work  is  quite  heavy,  the  outside  will  heat  before  the 
interior,  and  there  will  be  considerable  difference  in 


PREHEATING  AND  ANNEALING  135 

the  amount  of  expansion.  When  such  conditions  exist, 
we  are  in  danger  of  having  breaks  in  cooling.  The 
remedy  is  to  heat  slowly,  so  that,  within  or  without, 
the  distribution  of  heat  may  proceed  in  a  uniform 
manner.  Slow  heating  is  especially  to  be  advised 
where  there  is  a  combination  of  thin  and  thick  parts, 
otherwise  we  may  expect  severe  strains  and  perhaps 
breaks. 

After  completing  the  weld,  great  care  should  be 
taken  in  cooling  the  castings.  Safe  cooling  is  slow 
cooling.  Cooling  may  be  retarded  by  the  free  use  of 
sheet  asbestos  as  covers,  or  the  castings  may  be  buried 
or  packed  in  hot  ashes  or  sand.  Apart  from  the  pre- 
heating for  reasons  already  explained,  it  is  also  very 
valuable  as  to  time  and  cost  of  making  the  weld, 
which  may  be  reduced  from  30  to  50  per  cent  by 
previously  heating  the  pieces  to  be  welded. 

In  welding  cast  iron,  such  as  automobile  cylinders 
and  machinery  parts  of  similar  character,  it  is  neces- 
sary to  preheat  the  part  which  is  to  be  welded  to  a 
temperature  which  is  slightly  below  a  dull  red  heat, 
or  to  a  higher  heat,  if  there  are  no  parts  that  will  be 
injured  by  such  heat.  This  heat  should  be  applied 
gradually,  and  when  the  whole  object  has  been  suf- 
ficiently preheated,  the  welding  can  be  done. 

The  furnace  or  muffle  is  built  of  fire  brick  to  a  suit- 
able size  for  the  particular  part  to  be  handled.  A  re- 
movable cover  of  asbestos  or  sheet  metal  is  used.  After 
the  weld  has  been  made  the  article  should  be  heated 
again  and  allowed  to  cool  gradually  and  evenly  to 
prevent  cracking  and  to  make  the  material  in  the  weld 
less  hard  and  brittle. 

As  a  general  rule,  it  is  possible  to  overcome  the 
effects  of  local  heating  by  foreseeing  the  manner  in 


136  OXY-ACETYLENE  WELDING  AND  CUTTING 

which  they  will  manifest  themselves,  and  so  controlling 
them  to  the  extent  that  they  have  no  bad  results. 

Expansion  and  contraction  cannot  be  overcome  by 
force;  the  phenomena  manifest  themselves  whatever 
one  does,  and  it  is  perfectly  useless  to  try  to  oppose 
them.  The  method  is  to  avoid  or  limit  their  conse- 
quences. 

Figure  65  will  serve  to  illustrate  several  methods 
of  dealing  with  this  important  matter.  Assume  that 
the  bar  shown  in  the  upper  portion  of  the  illustra- 


C  •.„.-" 
. 

Figure  65 

tion  is  to  be  welded  at  the  spot  designated  by  the 
dotted  circle.  No  bad  effects  of  expansion  or  contrac- 
tion are  to  be  feared  when  it  is  free  to  expand  or  con- 
tract. No  precautions  are  necessary  to  overcome  the 
expansion  and  contraction  in  this  case.  But  suppose 
that  the  same  bar,  having  the  same  break,  is  located, 
for  example,  in  the  middle  of  the  frame  shown  in  the 
lower  portion  of  Figure  65,  and  must  be  welded.  No 
bad  effects  of  expansion  need  be  feared,  since,  on 
heating  to  fusion  the  edges  to  be  welded,  the  expan- 
sion takes  place  and  the  edges  to  be  welded  approach 


PREHEATING  AND  ANNEALING  137 

each  other,  the  metal  in  fusion  offering  practically  no 
resistance  to  this  expansion. 

But  the  weld  is  completed,  and  the  metal  com- 
mences to  cool  and  contract.  Now  the  bar  which  was 
free  to  expand  does  not  offer  the  same  freedom  to 
contraction,  since  the  two  extremities  of  the  bar  are 
fixed  solidly  to  a  frame  which  was  not  previously 
heated  and  consequently  is  unchanged. 

If  the  metal  is  ductile,  elastic,  the  contraction  of 
the  parts  heated  will  not  produce  a  break,  but  simply 
a  deformation  or  strain  corresponding  to  the  linear 
value  of  the  contraction.  This  would  often  be  the 
case,  for  example,  with  mild  steel.  If  the  piece  was 
of  cast  iron,  cooling  would  probably  produce  a  break 
in  the  welded  portion. 

A  break  will  frequently  occur  in  those  metals  which 
are  ductile  at  ordinary  temperatures,  but  whose 
strength  when  hot  is  extremely  low,  copper,  for  ex- 
ample; it  takes  place  during  cooling  in  that  part 
which  remains  at  the  highest  temperature. 

The  realization  of  welds  in  such  metals  is  possible. 
All  that  is  required  is  reflection  and  adjustment. 

One  could  raise  the  whole  piece  to  a  high  tempera- 
ture before  welding,  and  thus  produce  expansion  in 
the  entire  mass,  and  in  this  way  equal  contraction. 
But,  as  a  matter  of  fact,  complete  heating  is  not  neces- 
sary. It  is  sufficient  to  heat,  simultaneously  with  the 
operation  of  welding,  the  parts  B  and  C  of  the  frame 
and  thus  obtain  equal  expansion  to  that  of  the  broken 
bar;  then,  on  cooling,  the  contraction  is  of  equal  im- 
portance in  the  case  of  the  two  parallel  bars  and  the 
repaired  bar.  Therefore  there  is  no  strain  in  the 
metal  or  break. 

Suppose  it  were  impossible  to  heat  the  frame  at  B 


138  OXY- ACETYLENE  WELDING  AND  CUTTING 

and  C.  Other  methods  are  at  the  disposal  of  the 
welder;  for  example,  a  slight  separation  of  the  two 
bars  D  and  E  by  bending  separates  the  two  edges  to 
be  welded.  This  done,  proceed  to  weld,  and  at  the  end 
of  the  operation,  that  is,  as  soon  as  contraction  com- 
mences, due  to  cooling,  remove  the  keys,  wedges,  or 
screw  jacks  from  between  the  sides  D  and  E.  The 
return  of  the  bent  bars  to  their  original  position 
annuls  the  effect  of  contraction  in  the  welded  bar,  and 
thus  welded  it  should  be  free  from  strains,  deforma- 
tions, or  breaks. 

Another  method  is,  although  the  success  depends 
upon  the  thickness  of  the  metal,  to  cut  the  frame  at  F, 
execute  the  weld  of  the  bar,  and  then  weld  at  F,  the 
effects  of  contraction  being  least  to  be  feared  at  this 
part.  Sometimes  it  is  necessary  to  break  a  piece  in 
order  to  repair  it. 

This  example  shows  the  importance  which  the 
welder  should  attach  to  foreseeing  the  effects  of  ex- 
pansion and  contraction  during  the  execution  of  the 
weld  and  on  cooling.  And  this  is  evidently  part  of  the 
preparation,  since  it  is  not  possible  to  guard  against 
the  consequences  of  these  phenomena  once  the  weld- 
ing has  commenced.  The  devices  to  be  followed  vary 
in  each  case. 

Heating  Agents. — The  heating  agent  used  in  the 
ovens  already  mentioned  is  wood  charcoal,  or  wood 
charcoal  mixed  with  coke.  Fuels  of  this  type  have 
many  disadvantages.  Their  heat  is  generally  badly 
utilized  and  imparted  in  a  rather  irregular  manner  to 
the  articles  to  be  repaired.  Again,  the  residue  of 
combustion  can  be  deposited  in  the  cracks  or  bevel; 
and  lastly,  the  articles  being  generally  welded  while 
in  the  oven,  the  heat  and  smoke  are  an  inconvenience 


PREHEATING  AND  ANNEALING  139 

to  the  welder.  Much  more  satisfactory  results  are 
obtained  by  the  use  of  powerful  burners  in  which 
benzine,  gasoline,  kerosene  or  heavy  oils  can  be  used. 
It  is  not  economical  to  use  the  oxygen  from  the  cyl- 
inders when  a  sufficient  supply  can  just  as  easily  be 
drawn  from  the  air  to  serve  these  burners. 

In  some  cases  advantage  can  be  taken  of  the  large 
bunsen  burners  of  acetylene  which  are  made  for  indus- 


Fig.  66. — Group  of  Acetylene  Bunsens  for  Preheating1 

trial  heating  and  which  are  arranged  to  suit  the  re- 
quirements of  the  welder.  Figure  66  shows  such  an 
arrangement.  It  is  often  the  case  that  the  articles  to 
be  welded  do  not  have  to  be  preheated  in  an  oven,  but 
do  require  to  be  heated  to  a  high  temperature  in  the 
vicinity  of  the  weld,  and  further,  it  is  often  desirable, 
after  welding,  to  heat  the  line  of  the  weld. 

Figures  67  and  68  show  two  styles  of  portable  pre- 
heating and  annealing  burners  adapted  to  this  service. 
The  heater  shown  in  Figure  67  is  to  be  preferred  in 


140 


OXY-ACETYLENE  WELDING  AND  CUTTING 


shops  that  are  equipped  with  compressed  air,  since  it 
can  be  operated  under  any  pressure  varying  from  10 


Fig.  67. — Portable  Preheater  and  Annealer.     Compressed 
Air  Type 


Fig1.   68. — Portable  Preheater  and  Annealing  Device 

to  120  Ibs.  Any  grade  of  fuel  oil,  crude  oil,  kerosene, 
etc.,  is  adapted  for  use  in  it.  Table  V  gives  sizes  and 
other  details  relative  to  this  device. 


PREHEATING  AND  ANNEALING 

TABLE  V. 


141 


No. 

Capacity 
of  tank 

Length 
of  hose 

Oil   con- 
sumption 
per  hour 

Air  consumption 
cubic   feet   free 
air  per  minute 

Shipping 
weight 

Weight  of 
burner 

2 

15  Gal. 

24  ft. 

3  Gal. 

15 

100  Ibs. 

10  Ibs. 

4 

12  Gal. 

24ft. 

2  Gal. 

12 

90  Ibs. 

6  Ibs. 

5 

10  Gal. 

24  ft. 

IGal. 

8 

85  Ibs. 

3  Ibs. 

Figure  68  shows  a  portable  preheater  and  annealing 
burner  which  is  entirely  independent  and  self  con- 
tained, having  a  hand  air  pump  built  into  the  tank. 
This  device  is  designed  for  field  and  shop  work  when 
compressed  air  is  not  available  or  convenient.  It  is 
intended  for  kerosene  only,  the  flame  being  easily 
regulated  as  desired.  Before  operating  this  burner  it 
is  necessary  to  obtain  25  to  50  Ibs.  air  pressure  with 
the  hand  pump.  The  burner  operates  approximately 
two  hours  with  a  single  pumping.  Table  VI  gives 
capacities  and  other  details. 

TABLE  VI. 


No. 

Capacity    of 
Seamless 
tank 

Length   of 
hose 

Oil  consumption 
per  hour 

Shipping 
weight 

Weight 
of  burner 

7 

10  Gal. 

12  ft. 

IGal. 

80  Ibs. 

5  Ibs. 

8 

12  Gal. 

12  ft. 

2  Gal. 

95  Ibs. 

6  Ibs. 

9 

15  Gal. 

12ft. 

3  Gal. 

110  Ibs. 

8  Ibs. 

Manufacturers  also  make  a  special  preheating  torch 
for  use  in  localities  where  both  compressed  air  and 
illuminating  gas  are  obtainable.  This  torch  is  so  de- 
signed as  to  mix  the  gas  and  air  in  proportions  to 
give  a  large  hot  flame. 

To  Restore  Iron  and  Steel. — In  welding  iron  and 
steel,  after  completion  of  the  weld,  bury  the  work  in 


142  OXY-ACETYLENE  WELDING  AND  CUTTING 

ashes  or  lime  until  thoroughly  cooled,  then  reheat  the 
article  again  until  it  is  red.  Apply  a  magnet  to  the 
part  welded.  If  the  magnet  is  attracted  to  the  article, 
turn  on  a  little  more  heat  until  the  magnet  is  no 
longer  attracted.  As  soon  as  this  occurs,  discard  the 
use  of  the  magnet,  but  keep  heating  the  article  for 
about  two  minutes,  then  bury  the  piece  again  until 
thoroughly  cold.  This  will  restore  the  piece  to  the 
same  condition  as  it  was  before  the  break.  If  the 
workman  does  not  do  this  the  grain  of  the  metal  will 
be  coarse  where  the  weld  is,  and  will  break  more 
quickly  than  if  it  is  restored  as  above.  If  the  work  is 
done  as  explained,  the  grain  of  the  metal  will  be  fine 
and  will  have  its  original  strength  and  toughness. 

Goggles. — Metals  in  fusion  under  the  action  of  the 
torch  emit  extremely  bright  light  which  fatigues  the 
eyes  and  prevents  the  welder  following  the  course  of 
the  work.  It  is  important  therefore  for  him  to  wear 
special  glasses,  smoked  or  colored,  so  as  to  dim  the 
brightness  of  the  incandescent  metals,  protect  his 
sight  and  enable  him  to  follow  the  work  properly. 
This  precaution  is  absolutely  indispensable  and  any 
welder  who  operates  without  glasses  is  courting  ser- 
ious trouble  and  early  loss  of  ability  to  handle  this 
work.  These  glasses  also  serve  to  protect  the  eyes 
from  particles  of  oxide  that  are  projected  from  the 
weld.  It  is  a  difficult  matter  to  indicate  the  exact 
color  of  glasses  to  be  used  since  this  depends  on  the 
sight  of  the  user  and  the  nature  of  the  work.  The 
use  of  very  large  torches  and  those  for  cutting 
obviously  requires  very  dark  glasses  and  this  rule 
also  applies  to  certain  fluxes  which  emit  bright  light. 
The  glass  should  be  sufficiently  dark  to  prevent  the 
eyes  from  becoming  fatigued,  but  not  dark  enough  to 


PREHEATING  AND  ANNEALING  143 

strain  the  sight.  The  settings  of  the  glass  also  differ. 
There  are  a  number  of  different  patterns  to  choose 
from,  depending  on  the  distance  of  the  glass  from  the 
eye,  the  circulation  of  air  around  the  eye,  etc.  For 
special  work,  goggles  have  been  designed  that  protect 
the  neighborhood  of  the  eyes  and  the  nose  by  means 
of  a  mask. 

Torch  Lighter. — A  flame  of  some  kind  is  necessary 
near  the  welder  while  he  works  for  the  purpose  of 
lighting  and  re-lighting  the  torch.  A  small  flame  of 
acetylene  or  illuminating  gas  fixed  to  the  wall  is  gen- 
erally used.  This  is  better  than  a  candle  because  the 
gas  flame  is  not  easily  extinguished  by  the  torch. 

Accessories. — Autogenous  welding  installations  also 
contain  certain  accessories  used  by  the  welder.  These 
accessories  vary  according  to  the  work  to  be  done> 
such  as  the  tongs  for  moving  the  warm  articles,  wedges, 
keys,  hammers  and  mallets,  clamps,  etc. ;  also  vices,, 
anvil  and  accompanying  tools ;  water  vessel,  waste,  etc. 

For  welds  of  great  thickness,  and  for  welding  ar- 
ticles in  or  on  the  ovens,  the  welder  should  have  gloves, 
and  a  table  covered  with  asbestos;  also  plates  of  the 
same  material, to  protect  him  from  the  radiant  heat. 
Lastly,  there  is  the  rack  for  the  blowpipes  and  a  shelf 
for  the  fluxes,  welding  rods,  spare  parts,  etc.  A  card 
containing  advice  and  practical  hints  should  be  placed 
by  the  side  of  every  welding  table. 


CHAPTER  X 

OPERATING    A   WELDING   INSTALLATION 

Having  studied  at  some  length  the  gases  used  for 
obtaining  autogenous  welds,  and  also  all  the  various 
apparatus  and  equipment  required  for  a  complete 
welding  installation,  it  is  now  in  order  to  deal  with 
methods  of  operation. 

Installations  using  acetylene  at  low  pressure  and 
medium  pressure  will  first  be  taken  up,  after  which 
methods  of  working  with  high  pressure  equipment, 
in  which  the  acetylene  generator  is  replaced  by  the 
cylinder  of  gas  under  pressure  and  redlining  this 
pressure  with  the  special  valve  instead  of  the 
hydraulic  valve,  will  be  discussed. 

Testing  the  Plant. — If  the  plant  has  just  been 
erected,  or  cleaned,  or  if  it  has  been  standing  idle 
for  some  time,  the  first  thing  to  do  is  to  drive  all 
the  air  out  the  piping  and  parts  until  a  burner 
gives  a  normal  light.  The  piping  should  be  charged 
with  gas  right  up  to  the  cock  opening  into  the 
hydraulic  valve,  and  having  been  tested  by  methods 
previously  described,  should  show  no  leakage.  The 
oxygen  cylinder,  with  all  the  water  removed  from 
within  it,  and  the  valve,  with  all  the  dust  removed, 
are  to  be  placed  in  position.  The  reducing  valve  is 
also  placed  in  position,  as  already  explained,  and,  if 
upon  final  test,  there  is  no  leakage,  the  work  may 
proceed. 

Selecting  a  Torch. — A  torch  of  appropriate  delivery 
for  the  work  to  be  welded  is  chosen  and  connected 
l)y  means  of  the  flexible  tubes  to  the  reducing  valve 

144 


OPERATING  A  WELDING  INSTALLATION  145 

on  one  hand  and  to  the  hydraulic  valve  on  the  other. 
Care  should  be  exercised  to  avoid  becoming  con- 
fused regarding  the  tubes  on  the  torch.  The  tube 
designed  for  acetylene  generally  differs  from  the 
other  in  having  a  cock  which  serves  to  regulate  this 
gas. 

Testing  the  Hydraulic  Valve. — Having  completed 
the  attachment  of  the  flexible  tubes,  it  only  remains 
to  test  the  water  level  in  the  hydraulic  valve,  which 
should  be  done  at  each  working  point  at  least  once 
a  day  according  to  the  following  method : 

Open  the  gas  cock  leading  to  the  hydraulic  valve 
in  order  to  put  it  under  working  pressure,  then  open 
the  cock  to  gauge  the  level  of  the  water.  If  any 
gas  escapes,  the  water  level  is  too  low,  and  it  is 
necessary  to  add  more  through  the  open  tube ;  if 
only  water  escapes,  then  it  is  in  excess,  and  should 
be  allowed  to  escape  until  the  gas  bubbles  of  acety- 
lene appear.  The  following  method  is  more  positive 
and  more  sure: — (1)  Pour  water  into  the  open  tube 
so  that  it  is  in  excess ;  (2)  'charge  the  valve  with  gas  ; 
(3)  take  off  the  excess  water  by  the  gauge  cock 
until  the  appearance  of  a  stream  of  gases.  The 
hydraulic  valve  being  thus  prepared  to  carry  out  its 
function,  the  installation  is  in  starting  order. 

Starting. — In  starting,  proceed  as  follows : 

(1)  Open   very   slowly,   that   is,   do  not  unscrew 
sharply,  the  valve  of  the  oxygen  cylinder;  the  regu- 
lator screw   on  the  reducing  valve  being   entirely 
free,  and  the  outlet  valve  open,  as  previously  ex- 
plained (Fig.  54). 

(2)  Open  fully  the  acetylene  delivery  cock  on  the 
hydraulic  valve. 


146  OXY-ACETYLENE  WELDING  AND  CUTTING 

(3)  Open  fully  the  acetylene  delivery  cock  on  the 
blowpipe. 

(4)  Light  the  blowpipe  and  at  the  same  time  screw 
up  the  regulator  on  the  reducing  valve. 

(5)  Continue  to  screw  up  the  regulator  until  the 
reduced  pressure,  as  shown  on  the  gauge,  corresponds 
to  the  normal  working  of  the  blowpipe,  which  should 
be  known. 

At  this  moment  the  flame,  which  was  at  first  sooty, 
still  contains  an  excess  of  acetylene,  which  is  shown 
by  a  streaky  light  about  its  center,  in  the  extension 
of  the  exit  nozzle. 

The  variable  delivery  blowpipes  in  which  the 
orifice  of  the  oxygen  ejector  is  controlled  by  a 
needle  valve  are  managed  slightly  differently;  the 
regulating  screw  of  the  reducing  valve  is  entirely 
closed,  the  reducing  valve  is  then  set  to  the  pressure 
required,  next  light  the  acetylene  and  open  the 
needle  regulator  progressively  so  as  to  obtain  a  slight 
excess  of  acetylene.  Then  go  slightly  backwards  to 
obtain  the  normal  flame. 

Some  welders  regulate  the  reducing  valve  first, 
others  first  open  the  oxygen,  then  the  acetylene, 
and  afterwards  light  the  blowpipe.  Theij  is  noth- 
ing against  these  methods  when  the  operator  is  ex- 
perienced and  knows  thoroughly  the  details  of  the 
welding  installation.  As  a  general  rule,  it  is  better 
to  work  as  we  have  indicated,  free  to  give  the  vari- 
ous movements  almost  simultaneously. 

REGULATING    THE    FLAME 

The  flame  at  first  shows  an  excess  of  acetylene. 
Torches  which  show  otherwise  with  a  normal  pres- 
sure of  oxygen  and  with  the  acetylene  fully  open 


OPERATING  A  WELDING  INSTALLATION 


147 


are  deranged  or  obstructed  and  should  not  be  used 
in  this  condition  unless  it  is  known  that  the  defect 
is  one  of  obstruction  in  either  the  acetylene  piping 
or  the  hydraulic  valve.  In  either  case  it  should 
be  remedied  as  soon  as  possible. 
With  this  excess  of  acetylene  at  starting,  the  flame 


Figure   69. — Regulation   of   the   Flame.      Top   Figure,    Excess   of 

Acetylene;  Middle  Figure,  Normal  Flame;  Lower 

Figure,   Excess  of  Oxygen 

is  what  is  called  carbonizing.  In  order  to  render  it 
normal,  called  neutral,  it  is  necessary  to  close  par- 
tially either  the  acetylene  cock  on  the  torch  or  the 
one  at  the  exit  from  the  hydraulic  valve,  but  prefer- 
ably the  former.  The  streaky  light  disappears  by 
degrees  and  its  place  is  taken  by  a  white  halo,  which 
is  extinguished  in  turn  as  the  small  white  jet  in 
the  center  of  the  flame  next  the  nozzle  becomes  more 
pronounced.  This  is  a  neutral  flame. 


148  OXY-ACETYLENE  WELDING  AND  CUTTING 

If  the  acetylene  is  still  further  reduced,  the  white 
jet  diminishes  in  size  and  the  flame  becomes  oxidizing, 
that  is,  there  is  an  excess  of  oxygen.  Figure  69 
shows  clearly  these  three  conditions  of  the  flame  and 
is  self  explanatory.  It  is  evident  that  the  flame  can 
have  either  an  excess  of  acetylene  or  an  excess  of 
oxygen,  and  either  of  these  conditions  must  be  care- 
fully avoided  in  order  to  obtain  good  welds  and 
economy  in  their  execution. 

The  neutral  flame  is  obtained  by  reducing,  little 
by  little,  the  excess  of  acetylene,  but  this  reduction 
must  be  stopped  at  the  instant  all  the  white  halo, 
previously  referred  to,  has  disappeared. 

The  flame  is  then  characterized  by  a  small  violet- 
whitish  jet  of  very  clear  outline.  Its  base  is  at  the 
end  of  the  nozzle,  and  for  medium  delivery  blow- 
pipes its  length  is  only  %  inch  to  %  inch.  It  is  sur- 
rounded by  a  large  bluish  flame,  in  whicL  the  second 
phase  of  the  combustion  takes  place.  At  the  ex- 
tremity of  the  white  jet  we  obtain  the  highest  tem- 
perature of  the  flame. 

The  regulation  of  the  flame  is  in  a  way  the  regula- 
tion of  this  white  jet.  The  white  jet  should  be  as 
large  as  possible,  providing  that  its  outline  is  very 
sharp,  and  that  there  is  no  whitish  mantle  round  it. 

This  precise  point  must  be  carefully  sought  for, 
readjusting  several  times  during  the  work  to  make 
sure  of  this  point. 

Management  of  the  Torch. — It  is  very  important 
that  the  flame  should  remain  neutral,  that  is,  nor- 
mally regulated.  The  flow  of  the  gas  in  the  majority 
of  torches  for  low  pressure  acetylene  is  modified  by 
its  heating.  The  acetylene  expands,  arrives  at  the 
mixing  chamber  in  less  quantity,  and  the  flame 


OPERATING  A  WELDING  INSTALLATION  149 

gradually  becomes  oxidizing.  Some  welders  start 
with  a  slight  excess  of  acetylene,  a  scarcely  visible 
halo  surrounding  the  white  jet  which  disappears  as 
the  torch  becomes  heated.  An  excess  of  acetylene 
is  to  be  preferred  to  an  excess  of  oxygen,  only,  how- 
ever, as  a  choice  between  two  evils,  neither  being 
best  for  working. 

A  better  method  is  to  start  with  the  flame  neutral 
and  remedy  the  variation  after  the  torch  has  become 
heated.  Good  regulation  is  thus  obtained  with  two 
or  three  adjustments,  although  several  times  during 
the  weld  an  excess  of  acetylene  should  be  produced 
and  the  flame  then  brought  slowly  back  to  the  right 
point. 

In  making  certain  welds,  the  torch  is  liable  to  be- 
come too  hot  and  in  spite  of  all  possible  attention 
to  adjustment  the  flame  leaves  much  to  be  desired. 
One  remedy  for  this  condition  is  to  plunge  the  nozzle 
into  water  with  the  flame  extinguished  and  the  oxy- 
gen turned  on  slightly  so  that  the  flowing  of  the 
gas  opposes  the  entrance  of  the  water  into  the  orifice 
of  the  nozzle.  On  the  other  hand,  the  acetylene 
should  always  be  closed  in  order  to  avoid  the  forma- 
tion of  an  explosive  mixture  .above  the  water,  and 
the  blowpipe  should  never  be  plunged  in  while 
lighted. 

Defective  regulation,  bad  condition  of  the  blow- 
pipe, too  much  heating  of  the  nozzle,  irregularity 
of  the  flame,  projection  of  sparks  can  sometimes  re- 
turn the  flame  or  tend  to  return  the  flame  into  the 
interior  of  the  blowpipe. 

This  is  indicated  by  sharp  crackings,  which  in  the 
case  of  large  blowpipes  sometimes  produce  a  very 
loud  noise.  In  the  majority  of  cases  the  flame  be- 


150  OXY-ACETYLENE  WELDING  AND  CUTTING 

comes  normal  again  after  these  manifestations  of  the 
striking  back  into  the  interior ;  but  if  the  detonations 
are  renewed,  it  is  best  to  remedy  it  by  cooling  the 
blowpipe,  as  we  have  explained,  and  cleaning  the 
extremity  of  the  nozzle.  Certain  welders  find  it  con- 
venient to  increase  the  pressure  of  the  oxygen;  this 
will  obviously  prevent  the  return  of  the  flame. 

Sometimes  there  is  a  persistent  flashing  back  and 
burning  in  the  mixing  chamber  accompanied  by  a 
hissing  noise,  the  neutral  flame  disappearing  and  its 
place  being  taken  by  one  that  is  usually  smaller,  red- 
dish and  without  power  and  from  which  black  fumes 
issue.  In  such  a  case  the  gases  should  be  cut  off  im- 
mediately because  this  heats  the  interior  of  the 
torch,  incrusting  it,  and  may  destroy  or  damage  some 
of  the  parts.  Some  welders  simply  bend  the  actey- 
lene  tube,  cutting  off  this  gas  and  hold  it  closed  until 
the  internal  burning  has  stopped,  after  which  they 
release  the  tube  and  relight  the  flame  by  contact 
with  the  red  hot  metal.  The  safer  method  is  to  cut 
off  both  gases  by  the  nearest  cock. 

Handling  the  Torch. — In  proportion  to  the 'execu- 
tion of  the  weld,  that  is  to  say,  to  the  joining  of 
the  edges  by  melting  the  metal,  the  blowpipe  must 
be  moved  forward  very  slowly  and  with  great  care 
in  order  to  obtain  a  continuous  and  regular  weld. 

It  is  an  advantage,  of  course,  to  give  the  blow- 
pipe a  movement  such  that  the  two  edges  to  be 
welded  are  attacked  by  the  flame  in  such  a  manner 
as  to  bring  about  simultaneous  fusion.  The  move- 
ment, therefore,  should  be  frequent  and  regular. 

The  best  movement  is  to  make  the  small  white 
cone  describe  a  circular  movement,  the  diameter 
corresponding  to  the  molten  bath  obtained,  accord- 


OPERATING  A  WELDING  INSTALLATION 


151 


ing  to  the  thickness  to  be  welded,  so  that  this  move- 
ment, combined  with  the  advancing  one,  gives  a 
series  of  elliptical  curves,  the  locus  of  their  centers 
being  in  the  direction  of  the  line  of  welding. 


Figure  70. — Circular  Movement  of  the  Blowpipe  During  the 
Execution  of  Welds 

One  can  also,  especially  for  thick  pieces,  proceed 
in  half-circles,  or  play  the  flame  regularly  from  one 
side  to  the  other,  regulating  the  rapidity  of  the 
movement  according  to  the  melting  and  the  bath 


Figure  71. — Oscillatory  Movement  for  the  Execution  of  Welds  of 
Great  Thickness 

of  liquid  metal  obtained.  The  welding  is  done  by 
pushing  the  torch  and  not  by  pulling  it  except  in 
the  cases  where  the  two  edges  touch  each  other  com- 
pletely, and  for  thin  pieces  (tubes,  for  example),  a 


152 


OXY-ACETYLENE  WELDING  AND  CUTTING 


movement  from  side  to  side  is  indispensable.  Ac- 
cording to  the  metal,  its  thickness  and  shape,  the 
welder  should  give  a  regular  and  careful  movement. 
Figures  70  and  71  illustrate  the  different  movements. 


Figure  72. — Normal  Holding  of  the  Welding-  Rod 

Position  of  the  Welding  Rod. — The  welding  rod  is 
held  and  directed  by  the  left  hand  of  the  welder. 
If  it  is  a  question  of  a  thin  flexible  rod,  it  should  be 
bent  or  curved  so  that  the  flexibility  does  not  cause 
vibrations,  or  deviations  at  the  end. 


Figure  73.— Adding  Metal  from  the  Welding  Rod 

No  definite  instructions  can  be  given  with  regard 
to  the  inclination;  the  direction  depends  on  whether 
it  is  in  the  form  of  a  rod  or  thin  wire.  The  melting 
of  the  welding  rod  and  the  edges  of  the  weld  should 


OPERATING  A  WELDING  INSTALLATION  15S 

take  place  at  the  same  time,  so  as  to  cause  the  two 
metals  to  alloy  with  each  other  immediately.  If 
the  welding  rod  metal  flows  between  the  edges  of 
the  weld  before  they  are  melted,  the  joint  will  be 
bad.  It  is  then  an  adhesion,  not  a  weld. 

Acetylene  Regulation,  High  Pressure  Systems. — 
First,  valve  A  (Figure  74)  on  the  acetylene  tank 
must  gradually  be  opened  a  full  turn.  Turn  the 
handle  B  on  the  acetylene  regulator  until  the  de- 
sired pressure  shows  on  gauge  C,  which  should  be 
20  Ibs.  for  a  number  5  nozzle  and  15  Ibs.  for  num- 
bers 1,  2,  3  and  4. 

Open  the  needle  valve  or  cock  D,  then  the  torch 
valve  E.  The  acetylene  is  now  flowing  at  the  regu- 
lated pressure  through  the  torch.  After  securing  the 
supply  of  oxygen  as  follows,  the  flame  may  be 
lighted. 

Oxygen  Regulation. — The  following  table  gives  the 
proper  pressures : 

No.  1  Nozzle  Tip— 10  to  12  Ibs.  of  Oxygen. 

No.  2  Nozzle  Tip — 12  to  14  Ibs.  of  Oxygen. 

No.  3  Nozzle  Tip— 14  to  16  Ibs.  of  Oxygen. 

No.  4  Nozzle  Tip — 16  to  18  Ibs.  of  Oxygen. 

No.  5  Nozzle  Tip —  20  Ibs.  of  Oxygen. 

Open  the  oxygen  cylinder  valve  F  (Figure  74) 
gradually  to  a  full  turn  or  several  turns.  Turn 
handle  G  and  regulate  until  pressure  shows  on  gauge 
H  according  to  the  preceding  table  of  pressures. 
Open  the  regulator  needle  valve  I,  then  the  torch 
valve  J,  allowing  oxygen  to  pass  into  the  torch  and 
mix  with  the  acetylene. 

The  flame  may  be  lighted  as  the  oxygen  is  being 
turned  on  or  with  only  the  acetylene  flowing,  but 
do  not  allow  both  gases  to  flow  before  lighting. 


154 


OXY-ACETYLENE  WELDING  AND  CUTTING 


It  is  now  necessary  to  regulate  both  oxygen  and 
acetylene  by  the  valves  E  and  J  until  the  nozzle 


Figure  74. — Regulating  the  Acetylene  and  Oxygen 

shows  two  white  cones.    Figure  75  shows  the  appear- 
ance at  this  stage  for  each  number  of  nozzle.    Open 


OPERATING  A  WELDING  INSTALLATION 


155 


the  oxygen  torch  valve  until  the  large  cone  in  Figure 
75  comes  down  to  the  size  shown  on  Figure  76, 
which  is  correct  for  a  neutral  flame.  This  process 
may  be  repeated  to  advantage  by  again  turning  on 
more  acetylene  and  reducing  it  once  more  until  you 
have  the  desired  flame. 


Figure  75 


The  flame  is  now  in  proper  condition  for  welding 
steel,  iron  and  cast  iron.  Aluminum  requires  an 
excess  of  acetylene.  The  proper  regulation  of  the 
flame  should  be  continually  attended  to  inasmuch  as 
an  excess  of  acetylene  carbonizes  the  metal  and  an 
excess  of  oxygen  burns  it.  If  the  weld  has  a  fine 


156 


OXY-AGETYLENE  WELDING  AND  CUTTING 


spongy  appearance  it  is  certain  evidence  that  the 
flame  is  oxidizing  the  metal  or  burning  and  weaken- 
ing it. 

Always  unscrew  the  handle  on  the  oxygen  regu- 
lator and  on  the  acetylene  regulator  until  the  pres- 
sure is  entirely  removed  from  the  diaphragm  before 


Figure  76 


opening  the  tanks,  as  the  diaphragms  are  made  of 
thin  copper  and  soldered  into  place,  the  enormous 
pressure  striking  them  suddenly  will  cause  them  to 
leak.  Also  in  turning  on  or  opening  the  tanks, 
always  open  them  very  slowly,  so  that  the  hand 
creeps  around,  as  by  opening  them  suddenly  you  are 
liable  to  injure  the  hollow  spring  in  the  gauge.  Next 


OPERATING  A  WELDING  INSTALLATION  157 

see  that  there  is  no  leak  between  the  tanks  and  the 
regulators.  On  the  oxygen  this  may  be  ascertained 
by  holding  a  lighted  cigar  close  to  the  fittings,  if  it 
burns  brightly  there  is  a  leak.  Never  use  a  light 
near  the  acetylene  tank,  but  as  the  acetylene  gas 
has  an  odor,  you  will  be  able  to  detect  a  leak  very 
readily.  You  are  now  ready  to  screw  on  your  weld- 
ing tip,  select  the  size  tip  necessary  for  the  thickness 
of  metal  you  are  going  to  weld.  Now  turn  the  pres- 
sure on  the  acetylene  regulator  by  screwing  in  and 
light  the  torch.  See  that  you  have  enough  pressure 
on  the  acetylene  to  blow  the  flame  away  from  the  end 
of  the  tip  about  one-eighth  of  an  inch,  showing  one- 
eighth  of  an  inch  of  clear  space  between  the  tip  and 
the  luminous  flame.  Next  turn  on  enough  oxygen 
pressure  to  overcome  the  acetylene  and  draw  it 
down  to  a  clear  white  welding  cone ;  you  are  now 
ready  to  weld. 

Welding  Procedure. — Careful  attention  must  be 
paid  to  the  preparation  of  the  parts  to  be  welded. 
In  the  case  of  wrought  iron  and  steel,  the  pieces  to 
be  welded  must  generally  be  chamfered  off  at  an 
angle  of  45  degrees,  so  as  to  enable  the  flame  to  come 
into  direct  contact  with  the  whole  of  the  surfaces  to 
be  united,  then  direct  flame  to  center,  holding  torch 
perpendicular  to  lowest  point. 

The  groove  formed  by  the  chamfered  edges  is  filled 
by  fusing  in  steel  or  iron  wire  while  maintaining  the 
bottom  and  sides  in  a  state  of  fusion.  The  wire  must 
not  be  fused  in  unless  the  bottom  and  sides  of  the 
groove  are  also  in  a  state  of  fusion.  This  is  the 
secret  of  successful  welding. 

Commence  at  the  nearest  point  and  work  "away 
from  you/'  The  torch  should  be  maintained  at  a 


153  OXY-ACETYLENE  WELDING  AND  CUTTING 

uniform  distance,  having  cone  of  flame  just  touching 
work  (the  greatest  heat  is  just  on  the  point  of  the 
cone),  and  advance  slowly  and  regularly  and  work 
around  in  a  circle,  when  finishing. 

Where  the  maximum  strength  obtainable  is  re- 
quired, it  is  desirable,  if  possible  to  weld  from  both 
sides.  This  is  particularly  advantageous  with  heavy 
work,  as  it  allows  a  much  smaller  nozzle  to  be  used 
than  if  all  work  is  handled  from  the  one  side. 

If  small  round  holes  appear  in  iron  and  steel  they 
can  be  filled  by  heating  the  metal  around  the  hole 
to  a  white  heat  and  then  filling  by  two  or  three  quick 
passages. 

The  torch  must  never  be  held  still  for  a  moment, 
but  must  always  have  a  circular  or  oscillating  move- 
ment around  and  across  the  point  of  welding.  The 
welding  rod  must  be  held  down  in  the  joint  so  that 
it  is  at  all  times  touching  the  metal  being  welded 
and  must  never  be  applied  in  drops  from  the  end  of 
the  rod.  After  enough  has  been  melted  from  the 
rod  it  may  be  drawn  back  a  short  ways  out  of  the 
direct  welding  flame,  but  not  taken  from  the  work 
while  the  new  metal  is  worked  into  the  joint. 

In  welding  fractured  castings,  it  is  not  always 
necessary  to  chamfer  the  edges  of  the  pieces  to  be 
united.  It  is,  however,  necessary  that  the  material 
should  be  run  right  through.  This  can  be  done  by 
means  of  the  torch. 

In  dealing  with  complicated  castings,  such  as  auto 
cylinders,  precaution  has  to  be  taken  to  prevent  new 
fractures  developing  from  expansion  and  contraction, 
owing  to  internal  strains  set  up  by  the  intensity  of 
the  local  heat. 

Stopping  the  Installation. — This  implies  two  con- 


OPERATING  A  WELDING  INSTALLATION  159 

ditions,  (1)  the  temporary  extinguishing  of  the  torch 
to  enable  the  welder  to  examine  the  portion  of  the 
work  already  executed,  to  adjust  the  work  or  pre- 
pare another  weld,  or  (2),  a  definite  stoppage  for  a 
longer  period,  as  for  example,  between  the  hours  of 
work. 

In  the  first  case  the  temporary  closing  of  the  oxy- 
gen can  be  effected  by  means  of  the  valve  at  the 
outlet  of  the  reducing  valve,  while  the  acetylene 
may  be  cut  off  by  the  cock  on  the  torch,  on  the 
hydraulic  valve,  or  cylinder. 

For  a  longer  stoppage,  the  torch  should  be  first 
extinguished,  the  cylinder  valves  should  then  be 
closed  or  the  admission  valve  to  the  hydraulic  valve 
if  this  form  is  being  used.  This  done,  the  cocks  on 
the  torch  are  to  be  re-opened  to  allow  the  escape  of 
the  excess  gas  stored  by  pressure  in  the  various 
parts.  Finally,  the  regulating  screw  of  the  reducing 
valve  is  turned  out  until  free.  Also  notice  whether 
the  gauge  reads  zero. 

General  Advice. — The  welder  should  always  use  a 
blowpipe  (or  a  head-piece  in  the  case  of  blowpipes 
of  variable  delivery)  corresponding  to  the  kind  and 
thickness  of  the  metal  to  be  welded. 

Increasing  the  power  of  the  blowpipe  by  increasing 
the  pressure  of  the  oxygen  is  not  good  practice,  and 
would  not  be  indulged  in  by  a  conscientious  welder. 

Each  type  of  blowpipe  and  each  number  of  the 
same  type  corresponds  for  normal  working  to  a  pres- 
sure which  cannot  be  increased  without  increasing 
the  proportion  of  oxygen  and  oxidizing  the  welds. 
This  pressure  is  generally  given  by  the  makers  in 
their  catalogues ;  it  should  be  summarized  in  a  table 
fixed  near  the  welding  benches.  Endeavor  to  lower 


160  OXY- ACETYLENE  WELDING  AND  CUTTING 

the  working  pressure  of  oxygen  indicated,  but  never 
raise  it. 

The  welder  should  not  blindly  depend  on  the  read- 
ing of  the  reducing  gauge  for  obtaining  the  required 
pressure  of  oxygen;  sometimes  the  pointer  is  in  ad- 
vance or  behind;  in  case  of  doubt  it  is  necessary  to 
make  a  comparison  with  another  reducing  valve 
using  the  same  blowpipe. 

An  experienced  welder  may  not  consult  the  re- 
ducing gauge  for  obtaining  the  required  pressure  of 
oxygen,  but  regulates  by  the  flame,  keeping  the  pres- 
sure as  low  as  possible  for  a  normal  white  jet,  with- 
out too  great  a  rigidity,  and  without  any  return  to 
the  interior. 

An  autogenous  welding  installation  is  perfectly 
safe,  and  should  not  cause  any  accident  if  it  is  in- 
stalled, erected,  and  worked  according  to  the  condi- 
tions we  have  indicated.  All  ignition  by  leakage, 
blunders,  or  faulty  manipulation  produce  no  serious 
danger  if  one  immediately  closes  the  valve  of  the 
oxygen  cylinder,  and  the  cock  for  the  admission  of 
the  acetylene  to  the  welding  place.  Beware  of  oxy- 
gen leakages,  apparently  of  no  consequence,  which 
can  provoke  a  rapid  fire,  for  example,  of  the  clothes, 
by  a  simple  spark  coming  from  the  weld. 

Be  sure  the  welding  flame  is  neutral. 

Be  sure  the  part  to  be  welded  is  set  up  properly. 
A  poor  set  up  may  spoil  the  best  weld  for  practical 
use. 

Proper  heat  treatment  before  and  after  welding 
is  as  important  as  good  welding,  when  intricate  cast- 
ings, such  as  cylinders  and  crank  cases  are  being 
repaired. 

Avoid  hard  spots  in  cast  iron  welds  by  preheating 


OPERATING  A  WELDING  INSTALLATION  161 

before,  and  annealing  afterward.  Take  care  in  using 
sufficient  heat  in  welding  and  do  not  make  the  union 
between  casting  and  filling  material  too  sharp  and 
defined. 

Do  not  allow  drops  of  metal  to  fall  on  partially 
molten  metal. 

Use  the  best  grade  of  filling  material.  The  best 
is  none  too  good  when  all  the  expense  of  the  repair 
may  be  lost  by  a  weak  weld. 

When  preheating  aluminum  castings  for  welding, 
do  not  attempt  to  heat  in  one  place  only.  Keep  the 
burner  moving  to  spread  the  heat  uniformly. 

In  welding  steel  be  careful  that  the  metal  above 
the  weld  does  not  weld  together  and  leave  a  space 
that  is  not  welded.  A  "V"  shaped  groove  will  pre- 
vent this. 

Handling  Work  of  Varying  Thickness. — Auto- 
genous welding  is  not  easily  applied  to  the  joining 
of  pieces  varying  appreciably  in  thickness.  This  is 
due  to  the  fact  that  the  melting  of  the  two  edges  is 
not  equal  and  does  not  take  place. at  the  same  time, 
since  the  torch  is  too  powerful  for  the  thin  piece  or 
too  weak  for  the  thick  piece. 

This  difficulty,  however,  can  be  overcome  by  using 
two  torches,  the  one  raising  the  thick  piece  to  red 
heat  and  the  other  of  less  power  for  the  thin  plate. 
Another  method  consists  of  laying  a  heavy  piece  of 
heat  conducting  metal,  such  as  red  copper,  under 
the  thin  piece  so  as  to  carry  off  the  excess  heat. 

Thick  Pieces. — When  the  thickness  to  be  welded  is 
over  %  inch  it  is  advisable,  where  possible,  to  bevel 
both  sides  and  weld  from  both  sides.  If  the  joint 
warrants  it,  two  torches  may  be  used,  one  on  each 
side.  For  very  thick  work  the  welding  rod  metal 


162  OXY- ACETYLENE  WELDING  AND   CUTTING 

may  be  added  in  two  successive  layers,  being  care- 
ful to  secure  fusion  of  each  layer.  Another  method 
is  to  work  from  the  bottom  of  the  groove  in  steps. 

Thin  Pieces. — The  welding  of  thin  pieces  requires 
a  certain  amount  of  skill,  and  beginners  require  a 
great  deal  of  practice  before  they  are  able  to  do  it 
well. 

The  welding  of  thin  plates  under  T^  inch  is  par- 
ticularly difficult  on  account  of  the  separation  or 
warping  produced  by  expansion ;  also  the  least  excess 
of  heat  tends  to  produce  holes  which  are  difficult  to 
avoid  when  the  metal  is  very  thin. 

The  welder  should  carefully  watch  that  the  edges 
to  be  welded  do  not  overlap  each  other ;  if  one  can 
bend  them  up  a  small  height,  -/g  inch  for  example, 
the  execution  of  the  weld  becomes  much  easier ;  the 
metal  bent  over  serves  as  a  welding  rod,  and,  after 
welding,  the  line  of  welding  is  equalized  with  a 
hammer. 

Cleaning. — The  edges  to  be  welded,  and  their  im- 
mediate neighborhood,  that  is,  where  fusion  takes 
place,  should  be  cleaned  until  the  metal  is  wholly 
free  from  foreign  matter.  According  to  the  state  of 
the  surfaces  to  be  cleaned,  this  may  be  done  with  a 
grind  stone,  file,  scraper  or  simply  with  emery  cloth. 
The  rust  and  all  particles  that  are  detached  from 
the  cleaned  surfaces  must  be  removed  from  the  line 
of  welding,  and  especially  from  the  bottom  of 
the  bevel.  In  the  absence  of  mechanical  cleaning, 
chemical  agents  termed  fluxes  may  be  used.  These 
fluxes  generally  work  well,  but  it  is  advisable  to  pre- 
cede their  use  with  mechanical  cleaning  also. 


CHAPTER  XI 

METAL   WELDING  PRACTICE 

Fluxes. — It  is  not  always  possible  to  incorporate  in 
the  welding  metal  itself  those  elements  most  favorable 
for  combating  the  oxidation  of  the  welds,  and  the  loss 
of  certain  constituents,  etc.  Further,  certain  prod- 
ucts, notably  fluxes,  are  employed  previous  to  fusion 
of  the  metal,  and  having  a  different  object  than  the 
welding  metal ;  it  is  these  considerations  which  justify 
the  use  of  powders,  liquids,  or  pastes. 

The  powders  and  products  used  do  not  do  away  with 
the  necessity  for  a  special  welding  metal ;  they  are,  in 
the  majority  of  cases,  cleaning  and  deoxidizing  fluxes 
destined  to  prepare  the  edges  of  the  weld  and  elimi- 
nate, by  way  of  combination,  the  oxide  which  ia 
formed  during  welding. 

These  compositions  require  equally  great  care  in  the* 
preparation.  Although  their  use  in  greater  or  less, 
quantity  has  generally  no  effect  on  the  composition  of 
the  metal,  their  defective  manufacture  tends  to  pro- 
duce inconveniences  when  they  are  used,  and  in  con- 
sequence the  bad  execution  of  the  weld.  The  clean- 
ing fluxes  for  the  various  metals  are  most  convenient 
to  use  when  in  the  form  of  a  powder. 

The  flux  is  used  by  plunging  the  extremity  of  the 
welding  rod  into  the  box  or  bottle,  the  rod  having 
previously  been  heated,  but  not  to  excess.  Avoid 
throwing  the  powder  into  the  molten  metal  while  exe- 
cuting the  weld ;  the  supply  from  the  welding  rod  is 
alwrays  sufficient. 

163 


164  OXY-ACETYLENE  WELDING  AND  CUTTING 

The  usual  composition  of  fluxes  for  the  various 
metals  is  as  follows : 

Cast  Iron. — Equal  parts  of  carbonate  and  bicarbon- 
ate of  soda  to  which  is  added  10  to  15  per  cent  of 
.borax  and  5  per  cent  of  precipitated  silica. 

Ordinary  table  salt  may  also  be  used. 

Flux  should  not  be  used  unless  metal  does  not  run 
freely,  and  then  only  sparingly.  Too  much  flux  causes 
iron  to  harden  so  that  it  cannot  te  drilled  or  ma- 
chined. 

Steel. — Borax,  boracic  acid,  sodium  chloride  (salt). 
Do  not  use  flux  on  steel  unless  metal  will  not  run. 

Mild  Steel — Wrought  Iron. — Same  as  above,  used 
sparingly  or  not  at  all. 

Copper,  Brass  and  Bronze. — Same  as  above.  When 
used  for  brass  make  a  paste  with  a  little  water. 

Aluminum. — Lithium  chloride  15  per  cent. 

Potassium  45  per  cent. 

Sodium 30  per  cent. 

Potassium  flourile 7  per  cent. 

Bisulphate  of  Potassium.  3  per  cent. 

Plain  borax  may  also  be  used  for  aluminum. 

Welding  Rods. — These  are  rods  made  from  a  metal 
practically  the  same  in  composition  as  that  to  be 
welded.  They  are  made  in  sizes  adapted  to  the  nature 
of  the  welding.  For  very  light  work  the  diameter  of 
the  rod  may  be  as'  small  as  TV  inch  and  for  heavier 
work  this  diameter  increases  up  to  %  inch  or  more, 
toeing  usually  about  %  the  thickness  of  the  work. 

Their  composition,  of  course,  depends  on  the  metal 
to  foe  welded,  for  example,  aluminum  rods  are  made 
from  the  purest  aluminum  obtainable ;  for  iron  or  mild 
Bteel  the  rod  js  of  soft  iron;  for  copper  it  is  of  phos- 
phor copper  with  traces  of  aluminum ;  for  cast  iron 


METAL  WELDING  PRACTICE  165 

the  rod  is  cast  iron,  etc.  These  rods  may  be  purchased 
from  any  of  the  welding  apparatus  manufacturers. 

Steel  Welding. — The  welding  of  steel  presents  less 
difficulty  to  the  operator  than  any  other  metal  to  be 
welded.  It  runs  together  very  readily  and  in  this, 
connection  it  must  be  borne  in  mind  that  all  sections. 
of  steel  should  be  beveled  so  that  welding  can  begin  at 
the  bottom  or  in  the  center  of  thick  pieces.  Other- 
wise the  steel,  which  as  noted,  runs  together,  will 
weld  only  on  the  surface.  Flux  is  not  really  necessary 
with  steel. 

The  rod  for  steel  should  be  the  same  grade  or  better 
grade  than  the  pieces  to  be  welded.  In  thin  sheets, 
strips  may  be  cut  off  and  used  as  filling  rods,  or  wire 
may  be  twisted  together  to  make  the  rod. 

For  -£Q  inch  or  under  put  the  edges  together  and 
melt  through,  moving  your  welding  flame  in  small 
circles  to  flow  the  edges  together,  add  new  metal  from 
a  welding  wire  where  necessary. 

For  heavier  steel  grind  the  edges  so  that  you  will 
have  a  45°  Y,  melt  the  edges  together  seeing  that  the 
bottom  of  the  V  is  hot  enough  to  unite  thoroughly, 
then  add  enough  metal  from  your  steel  welding  rod 
to  fill  the  V  level  with  the  rest  of  the  sheet. 

When  welding  on  heavy  metal  it  is  economy  to  pre- 
heat the  sheet  or  casting  welded  with  a  natural  or 
artificial  gas  torch,  charcoal,  or  coke,  as  the  work  can 
be  done  much  faster  and  with  a  great  saving  of  oxy- 
gen and  acetylene  and  you  will  make  a  better  and 
stronger  weld.  In  seam  welding  where  the  metal  is 
thin  and  liable  to  warp,  start  welding  about  6  inches 
from  the  end,  leaving  the  far  end  open  about  %  inch 
to  the  foot  of  the  seam,  weld  across  the  sheet  and  re- 
turn and  finish  the  sjx  inches  starting  on  the  inside  and 


166  OXY-ACETYLENE  WELDING  AND  CUTTING 

working  towards  the  end.  Where  this  method  is  not 
practicable,  stick  the  sheet  every  six  or  eight  inches 
and  begin  welding  in  the  center  and  work  to  the  ends. 
Select  a  tip  large  enough  to  melt  the  metal  readily 
and  finish  your  weld  in  one  spot  and  move  on,  as  it  is 
very  bad  for  a  weld  on  any  metal  to  keep  the  flame 
in  one  place  too  long.  You  are  liable  to  burn  the 
metal  and  make  a  weak,  hard  weld. 

Steel  of  %  inch  and  less  in  thickness  can  be  welded 
without  the  addition  of  any  metal  from  a  rod.  When 
adding  material  to  heavier  work  do  not  commence 
until  the  part  to  be  welded  is  flowing  freely,  and  when 
in  this  condition  add  metal  from  the  rod,  being  sure 
that  the  rod  is  touching  the  work  at  all  times. 

Hold  the  torch  so  that  the  flame  strikes  the  end  of 
the  rod  and  the  work  at  the  same  time.  If  a  foam 
gathers  on  the  top  of  the  weld  while  welding,  throw 
the  flame  a  little  further  away  from  the  work  and  keep 
trying  this  until  the  metal  flows  freely  without  this 
foam  gathering.  Be  sure  about  this  as  it  is  very  im- 
portant. It  may  be  necessary  to  keep  the  flame  off  for 
about  ten  seconds. 

In  welding  a  crack  in  the  middle  of  a  heavy  steel 
sheet,  prepare  the  crack  by  chamfering  the  metal  on 
each  side  of  the  same  at  an  angle  of  45  degrees  to  the 
bottom,  then,  as  previously  directed,  apply  the  weld- 
ing torch  to  the  metal  beyond  the  end  of  the  crack 
until  it  is  expanded  enough  to  open  the  crack  per- 
ceptibly, and  make  the  weld  while  the  metal  is  in  this 
condition,  and  usually  it  will  be  found  that  the  ex- 
pansion has  been  sufficient  to  care  for  the  contraction  ' 
in  the  weld  when  cooling. 

When  the  weld  is  completed,  do  not  forget  to  pass 


METAL  WELDING  PRACTICE  167 

the  torch  over  it  and  the  surrounding  metal,  as  pre- 
viously instructed. 

Cast  Iron  Welding. — In  welding  cast  iron  preheat- 
ing is  essential  to  insure  a  soft  weld  free  from  blow 
holes.  For  auto  cylinders,  crank  cases,  and  all  similar 
castings,  it  is  imperative  to  preheat  the  casting  slowly, 
and  after  making  the  weld,  cool  slowly  either  by  turn- 
ing the  preheating  flames  down  gradually,  or  if  char- 
coal is  used,  cover  the  casting  to  keep  the  air  off  and 
let  the  fire  die  out,  or  by  removing  the  casting  from 
the  fire  and  when  hot  place  in  slack  lime  or  fine  ashes. 
It  is  also  well  to  heat  the  lime  or  ashes  before  placing 
the  casting  in  it. 

It  is  necessary  to  use  a  good  flux  in  cast  iron  weld- 
ing, one  that  will  throw  off  impurities  and  make  the 
metal  flow  freely.  Also  select  your  cast  iron  rods  with 
care,  using  only  soft  iron  high  in  silicon. 

If  the  piece  to  be  welded  is  of  such  form  that  it  will 
crack  in  cooling,  an  engine  or  pump  cylinder,  it  should 
be  preheated,  but  not  sufficiently  to  warp  the  metal, 
no  part  to  be  brought  to  a  dark  red  except  at  the  weld- 
ing point.  Charcoal  is  a  good  material  to  preheat 
writh,  as  the  heat  is  uniform. 

There  are  many  pieces  of  cast  iron  that  can  be 
welded  without  preheating,  but  where  it  is  convenient 
to  do  so,  it  is  advisable  to  preheat,  as  it  saves  the  oxy- 
gen and  acetylene  gases. 

If  the  metal  is  more  than  i/4  inch  in  thickness,  the 
edges  should  be  champfered  to  about  45  degrees.  In 
the  heavier  welds,  it  is  desirable  to  leave  three  slight 
points  of  contact  to  assist  in  adjusting  and  holding 
the  broken  parts  in  their  exact  position  while  welding. 

To  make  the  weld,  the  torch  should  be  passed  for 
some  distance  around  the  fracture  and  then  directed 


168  OXY-ACETYLENE  WELDING  AND  CUTTING 

onto  the  fracture  until  the  metal  begins  to  run.  Then 
add  cast  iron  from  the  cast  iron  welding  rod,  but  use 
flux  only  if  the  metal  does  not  flow  well.  Never  at- 
tempt to  re-weld  pieces  that  have  already  been  welded 
and  broken  without  cutting  away  all  the  old  metal. 
To  weld  cast  iron  to  steel,  use  cast  iron  rods  and  heat 
the  steel  to  the  melting  point  first,  as  cast  iron  melts 
at  a  lower  temperature.  Use  but  very  little  flux. 

To  Weld  an  Engine  or  Pump  Cylinder. — First  take 
a  diamond  point  chisel  and  chip  all  around  the  frac- 
ture until  almost  through,  then  have  a  forge  large 
enough  to  start  a  fire  all  around  the  cylinder,  not  a 
large  fire,  but  a  fair  size,  of  charcoal.  Keep  this  fire 
going  for  at  least  four  hours,  but  do  not  let  it  get  any 
larger  and  be  sure  to  have  the  piston  opening  of  the 
cylinder  down,  and  the  fire  well  in  under  so  that  the 
heat  will  go  up  through  the  dome.  This  will  dis- 
tribute the  heat  evenly  all  through  the  castings.  Have 
asbestos  paper  and  keep  the  piece  covered  all  the  time 
from  start  to  finish,  leaving  an  opening  just  large 
enough  to  weld  with.  At  the  end  of  four  hours  the 
piece  should  be  ready  to  start  welding.  At  this  time 
put  a  little  charcoal  all  around  the  fire.  Then  lay 
the  engine  cylinder  down  as  level  as  possible  with  the 
fracture  up.  It  would-  be  well  to  have  an  assistant 
ready  as  soon  as  the  weld  is  started.  In  starting  the 
weld,  start  at  the  back  end  of  the  fracture,  if  there 
is  a  back  part.  The  piece  will  start  to  expand  as  soon 
as  the  welding  begins.  If  this  was  not  done  it  would 
crack  before  the  weld  was  finished.  So  if  there  is  an 
opening  start  at  the  back  end  and  finish  welding  at 
the  opening.  If  it  is  a  round  fracture  and  a  piece 
broken  out,  start  welding  anywhere.  Play  the  torch 
all  around  the  fracture  first  and  then  bring  the  small 


METAL,  WELDING  PRACTICE  169 

white  cube,  just  the  point  of  it,  on  the  end  where  it  is 
intended  to  start,  at  the  same  time  have  east  iron  weld- 
ing stick  resting  where  the  weld  is  to  begin ;  then  have 
the  white  cube  spoken  of  strike  the  piece  to  be  welded 
and  the  welding  stick  at  the  same  time.  It  may  be 
necessary,  if  the  cylinder  is  badly  burned,  when  it  is 
nearly  at  a  melting  point  to  push  gently  on  the  weld- 
ing rod.  This  is  to  lift  up  the  iron  and  let  the  heat 
get  under  it.  Do  this  carefully  so  as  not  to  get  too 
much  weight  on  the  welding  rod,  or  it  will  push  it 
through  and  make  a  hole.  Keep  the  torch  right  close 
all  the  time.  As  soon  as  the  weld  is  finished  draw  the 
fire  closely  together.  Have  your  assistant  ready  with 
tongs  or  something  suitable,  and  turn  the  weld  right 
over  into  the  fire  so  that  it  will  get  the  full  heat  of 
the  fire.  If  it  is  a  long  weld,  when  about  one  inch 
is  finished  place  a  piece  of  asbestos  paper  over  it  to 
keep  the  cold  air  from  striking  it.  Keep  doing  this 
as  fast  as  you  proceed  until  the,  piece'  is  finished. 
Then  cover  it  up  very  carefully,  so  that  no  air  can 
strike  it,  and  under  no  circumstances  uncover  or  dis- 
turb it  until  the  next  day.  This  will  keep  it  from 
cracking  generally,  but  sometimes  it  will  crack  after 
the  greatest  precautions  are  taken.  The  only  remedy 
is  to  chip  it  out  again  and  begin  all  over. 

Malleable  Iron  Welding.-±-PaYts  of  malleable  iron 
are  handled  in  much  the  same  manner  as  cast  iron 
parts  in  preparation  for  welding.  It  is  usual  to 
strengthen  the  weld  as  much  as  possible  by  building 
up  from  the  rods.  Nickel  steel  may  be  used  for  filling 
in  the  bottom  of  the  crack  or  bevel,  cast  iron  being 
placed  on  top.  Wherever  the  metal  is  to  be  drilled 
or  otherwise  worked  there  must  be  no  junction  of  the 
new  metal  with  the  old.  If  it  is  necessary  to  avoid 


170  OXY-ACETYLENE  WELDING  AND  CUTTING 

this  junction  coming  at  a  place  that  must  be  worked 
or  machined,  a  greater  amount  of  old  metal  must  first 
be  cut  away  and  the  whole  space  filled  from  the  rod. 

As  a  reinforcement  it  may  be  necessary  to  strap 
the  parts  with  wrought  iron  or  steel  bands  welded  to 
the  body  of  the  casting.  Bear  in  mind  that  heating 
malleable  iron  turns  it  to  ordinary  cast  iron  at  that 
point. 

Malleable  iron  is  the  most  refractory  metal  that  the 
welder  has  to  contend  with.  It  has  been  found  that 
Swedish  iron  with  a  small  copper  wire  twisted  around 
it  is  the  best  for  some  malleable  castings,  while  it  will 
not  work  at  all  on  others.  "When  this  fails,  use  man- 
ganese bronze  and  where  possible  reinforce  by  leaving 
the  welded  joint  heavier  than  the  rest  of  the  casting. 
For  a  flux  use  as  on  cast  iron,  but  do  not  heat  the  mal- 
leable iron  as  hot  as  the  cast  iron,  merely  hot  enough 
to  coat  freely  with  the  bronze,  then  fill  in. 

Aluminum  Welding. — The  welding  of  aluminum  re- 
quires considerable  skill  and  experience  before  suc- 
cessful work  can  be  expected  on  intricate  parts.  The 
manner  of  making  the  weld  is  slightly  different  than 
is  used  with  welding  of  cast  iron,  due  to  the  fact  that 
when  aluminum  is  heated,  an  oxide  film  is  formed, 
which  prevents  the  metal  running  together  and  form- 
ing a  suitable  weld.  To  overcome  this,  the  aluminum 
filling  rods  must  be  inserted  into  the  molten  alumi- 
num, which  is  being  welded,  and  moved  about  rapidly, 
something  similar  to  puddling,  in  order  to  break  up 
this  oxide  film  and  allow  the  aluminum  to  run  to- 
gether. A  flux  has  also  proven  to  be  of  advantage  in 
this  connection,  where  before,  practically  all  of  this 
work  was  done  without  the  use  of  a  flux. 

While  aluminum  melts  at  a  lower  point  than  any  of 


METAL  WELDING  PRACTICE  171 

the  other  metals  mentioned,  it  is  necessary  to  have  a 
high  concentrated  heat  to  melt  it  at  the  point  to  be 
welded  and  not  get  it  too  soft  on  each  side  of  the 
weld.  As  aluminum  does  not  show  heat  as  other 
metals  do,  it  is  necessary  to  go  by  the  sense  of  touch. 
Use  a  spatula  or  spoon  made  by  flattening  the  end  of 
a  piece  of  steel,  scrape  the  casting  where  you  are  heat- 
ing it  until  it  softens,  and  add  new  metal  from  your 
cast  welding  rod,  always  making  sure  that  your  metal 
underneath  is  soft  enough  to  unite  with  the  metal 
you  are  adding  to  it.  Use  your  steel  spoon  freely  and 
work  the  edges  together.  When  you  have  finished 
the  wreld  scrape  off  the  surplus  aluminum  with  the 
spoon. 

A  larger  tip  is  necessary  for  welding  a  section  of 
aluminum  than  would  be  required  for  the  same  sec- 
tion of  steel  or  cast  iron.  This  is  due  to  the  fact  that 
aluminum  conducts  heat  very  rapidly.  With  the 
proper  size  tip  in  use,  it  is  necessary  to  melt  a  con- 
siderable portion  of  aluminum,  which  is  being  held  up 
in  shape  by  the  fire  clay  form.  Now  the  extra  metal 
can  be  added  from  the  filling  rod  and  stirred  or 
puddled  with  this  rod  to  break  the  oxide  film,  which 
forms  when  aluminum  is  melted. 

A  flux,  for  use  in  this  connection,  will  be  found  very 
valuable  for  breaking  up  this  film.  In  fact,  by  using 
this  flux,  bosses  can  readily  be  built  up  at  any  desired 
point.  This  is  something  that  could  not  be  done  be- 
fore a  flux  for  welding  aluminum  came  into  general 
use. 

All  precautions  should  be  taken  to  have  work  se- 
curely fastened,  or  harnessed.  For  instance,  in  the 
welding  of  a  hole  in  the  side  of  a  crank  case,  it  is  cus- 
tomary to  clamp  a  shaft,  which  approximates  the  size 


172  OXY- ACETYLENE  WEEDING  AND  CUTTING 

of  the  bearings  (less,  of  course,  the  cast  metal  bear- 
ings, which  would  melt  out) ,  into  the  crank  case  bear- 
ing supports,  in  order  to  insure  perfect  alignment  of 
the  bearings.  Angle  irons  are  bolted  to  the  flanges 
where  connection  is  made  to  the  other  half  of  the  crank 
case  in  order  to  insure  perfect  alignment  of  this  part. 

It  is  good  practice  to  place  a  sheet  of  paper  on  the 
inside  of  the  case  next  to  the  crack  to  be  welded.  This 
paper  prevents  the  fire  clay  from  getting  into  the 
crack.  Upon  this  is  placed  fire  clay  in  plastic  condi- 
tion, which  is  held  in  place  by  means  of  asbestos  fibre. 
This  makes  a  light  backing  or  mould  for  the  case  and 
can  be  easily  handled  without  fear  of  the  mould  or 
core  being  so  heavy  as  to  break  down  the  case  when 
heated  for  welding.  This  mould  should  be  large 
enough  to  cover  sufficient  area  around  the  crack  so 
that  the  aluminum  will  not  break  down. 

Aluminum  to  be  welded  should  be  well  scraped.  If 
the  weld  is  more  than  %  inch  in  thickness,  it  is  ad- 
visable to  chamfer  the  same.  Aluminum  should 
always  be  preheated  and  kept  covered,  except  where 
the  weld  is  being  made,  and  then  quickly  covered  with 
asbestos  paper  until  it  is  well  cooled. 

To  make  a  good  weld  in  aluminum,  heat  the  whole 
piece  slowly,  to  about  300°  or  400°  short  of  the  melt- 
ing point,  then  cover  the  pieces  with  asbestos  paper,  or 
by  other  means,  leaving  an  opening  where  the  weld  is 
to  be  made,  keeping  the  whole  piece  hot  until  the  weld 
is  completed.  After  the  weld  is  finished,  cover  the  piece 
completely  to  protect  it  against  drafts,  and  so  that  it 
will  cool  very  slowly,  to  prevent  shrinkage  cracks. 

It  will  be  noticed  when  putting  the  welding  flame 
on  the  aluminum  at  the  fracture,  that  the  aluminum 
does  not  run  together.  An  iron  rod,  of  which  the 


METAL  WELDING  PRACTICE  173 

point  is  flattened  and  bent  about  %  of  an  inch,  like  a 
small  poker,  and  pointed,  should  be  used  to  puddle  the 
aluminum,  and  this  rod  should  be  wiped  frequently,  so 
that  it  will  not  become  coated  with  aluminum.  A  jar 
should  be  provided  and  filled  with  a  saturated  solu- 
tion of  water  and  table  salt,  and  the  mixing  rod 
should  be  dipped  into  the  same  occasionally  while 
welding.  It  is  better  to  have  three  of  these  puddling 
irons  and  keep  them  in  the  salt  solution  while  using. 
In  this  way  you  always  have  cool  ones  ready.  Great 
care  should  be  taken  not  to  let  the  rod  reach  a  red 
heat,  as  this  would  cause  oxide  of  iron  to  form  on  the 
rod,  and  this  mixing  with  molten  aluminum  would 
make  a  defective  weld.  The  salt  remaining  on  the 
rod,  when  coming  into  contact  with  molten  alumi- 
num, forms  a  very  thin  film,  excluding  to  a  certain 
extent  oxidation  by  oxygen  contained  in  the  air. 

Aluminum  parts  must  always  be  preheated  and 
handled  in  a  similar  manner  as  automobile  cylinders, 
as  outlined  before,  with  the  exception  that  aluminum, 
of  course,  should  not  be  heated  to  such  a  high  tempera- 
ture, on  account  of  the  fact  that  within  122°  Fahr.  of 
the  melting  point,  the  metal  is  very  brittle  and  with- 
out strength.  It  is  customary  to  heat  up  these  cases 
thoroughly  until  they  will  melt  half  and  half  solder 
in  wire  form.  This  temperature  is  about  right  to  pre- 
vent cracking  occurring  on  account  of  expansion  and 
contraction  and  at  the  same  time,  the  aluminum  will 
possess  sufficient  strength  so  that  with  ordinary  han- 
dling, no  trouble  is  experienced  with  alignment  or 
failure  of  the  part. 

Great  care  should  be  used  in  preheating  crank  cases, 
transmission  cases,  etc.,  to  get  them  hot  enough  and 
yet  not  overheat  them  and  warp  them  out  of  shape. 


174  OXY-ACETYLENE  WELDING  AND  CUTTING 

It  will  be  found  that  clamping  liners  on  a  case  will 
greatly  aid  in  preventing  warping. 

Aluminum  Crankcase  Welding. — To  weld  aluminum 
properly  first  get  a  jar  and  put  a  handful  of  salt  in 
it.  Then  fill  it  up  with  water.  Next  make  some 
wrought  iron  pokers  about  15  inches  long  with  a  bend 
of  %  inch.  Have  the  point  sharpened  about  like  a 
lead  pencil.  Throw  a  ring  on  the  other  end  with 
which  to  handle,  to  make  it  easier  to  hold.  These  are 
the  things  that  will  be  needed  first.  Take  the  alumi- 
num casting,  put  it  in  a  large  forge  or  on  some  suit- 
able table,  and  set  it  up  on  bricks.  Then  build  a  small 
charcoal  fire  all  around  it.  Keep  this  fire  going  for 
about  an  hour  and  a  half. 

At  the  end  of  this  time  cover  the  piece  to  be  welded 
with  asbestos  paper,  leaving  an  opening  large  enough 
to  get  at  the  fracture.  Then  take  one  of  the  pokers 
in  the  right  hand  and  hold  the  torch  in  the  left  hand. 
Apply  the  flame  on  the  part  of  the  fracture  that  you 
are  going  to  weld  and  keep  poking  with  the  poker 
until  it  gets  soft.  When  it  begins  to  get  soft,  you 
can  puddle  it  until  you  get  almost  through  on  the 
other  side.  Keep  doing  this  all  the  way  along  until 
you  get  the  fracture  welded.  Never  start  welding  at 
the  opening,  always  start  at  the  back  end  and  work 
toward  the  opening,  finishing  there.  It  would  prob- 
ably be  a  little  rough,  but  you  can  play  the  flame  on 
it  and  keep  drawing  the  poker  over  it  and  keep 
smoothing  it  down  to  your  own  satisfaction.  Of  course 
add  metal  from  the  aluminum  welding  stick  from 
time  to  time  to  make  the  weld  higher  than  the  rest  of 
the  casting.  It  can  be  filed  down  to  size  afterwards. 
Then  turn  it  over  quickly  and  do  the  same  thing  on 
the  inside  as  on  the  outside.  Be  sure  not  to  uncover 


METAL  WELDING  PRACTICE  175 

the  piece  after  you  begin  to  weld,  or  a  cold  draft  may 
strike  it  and  it  will  break  again.  Do  not  cover  it  with 
asbestos  paper  before  starting  to  weld,  or  the  piece 
may  melt  on  the  parts  nearest  to  the  fire.  Do  not 
uncover  the  piece  under  any  circumstances  until  the 
next  day. 

We  would  strongly  advise  clamping  some  cast  iron 
straight  edges  on  the  face  of  the  castings  to  keep 
them  in  line.  These  straight  edges  should  be  at  least 
one  inch  thick  and  one  and  a  half  inches  wide,  and 
be  long  enough  to  extend  the  entire  length  of  the 
crankcase  face. 

Add  the  new  aluminum  from  rods.  These  rods  can 
stand  in  a  salt  solution,  or  be  dipped  occasionally. 

There  are  many  pieces  of  aluminum  that  can  be 
welded  without  preheating,  as  will  soon  be  learned  by 
the  experience  of  the  operator.  Lugs  or  projecting 
pieces  broken  completely  off  do  not  require  to  be  pre- 
heated. Pieces  broken  out  and  entirely  lost  can  in 
nearly  all  cases  be  fitted  in,  or  built  up  with  little 
difficulty. 

Welding  of  Brass,  Copper  and  Bronze. — To  weld 
copper  use  the  same  kind  of  a  flame  as  for  aluminum, 
but  a  much  larger  tip  and  flame  must  be  employed  for 
pieces  of  equal  size  because  of  the  greater  heat  radiat- 
ing power  of  copper.  Preheating  is  necessary  with 
large  pieces  of  copper,  otherwise  the  heat  of  the  torch 
would  be  absorbed  by  radiation  and  but  little  left  for 
fusion  of  the  metal. 

Copper  will  weld  at  about  1929°  Fahr.,  conse- 
quently the  flame  need  not  be  of  so  high  a  temperature 
as  for  steel  and  it  must  not  be  concentrated  on  so  small 
a  surface,  but  on  account  of  the  radiation  the  total 


17G  OX Y- ACETYLENE  WELDING  AND  CUTTING 

quantity  of  heat  will  be  even  greater.  Flux  is  not 
really  needed  with  copper. 

In  brass  welding  keep  the  point  of  the  dull  white 
flame  about  touching  the  weld,  according  to  the  thick- 
ness of  the  piece,  so  that  the  heat  will  not  be  suf- 
ficient to  burn  the  copper,  wrhich  is  in  the  brass,  and 
also  consume  the  zinc.  If  a  white  smoke  should  be 
created,  remove  the  flame,  as  this  indicates  that  too 
much  heat  is  being  used.  Use  flux  as  it  will  assist 
greatly  in  making  the  weld.  Use  flux  as  a  paste  by 
mixing  it  with  water.  Dip  welding  rod  in  the  paste 
and  apply  it  quickly  to  the  work. 

The  preparation  of  brass  and  bronze  castings  for 
welding  is  similar  to  that  for  cast  iron  castings.  The 
fracture  must  be  caped  out  so  that  the  welding  can 
start  at  the  center,  the  groove  being  filled  with  metal 
melted  from  the  filling  rod. 

The  filling  rod  should  be  of  approximately  the  same 
mixture  as  the  part  to  be  welded.  Brass  should  never 
be  used  as  filling  material  for  bronze  castings,  and  a 
strong  weld  expected.  Powdered  borax  or  boric  acid 
may  be  used  as  a  flux.  A  mixture  of  one-half  borax 
and  one-half  boracic  acid  gives  good  results. 

In  welding  brass  or  bronze  the  work  is  carried  out 
as  for  welding  cast  iron.  The  metal  surrounding  the 
groove  is  melted  and  the  filling  material  added,  drop 
by  drop,  as  it  is  melted  from  the  rod.  Be  sure  the 
metal  of  the  casting  is  in  a  molten  condition,  other- 
wise an  imperfect  weld  will  result.  Brass  welds  can 
be  easily  spoiled  by  burning  the  zinc  out  of  the  com- 
position. Care  should  be  taken  not  to  heat  beyond 
the  melting  point.  Flux  should  be  used  freely.  If 
the  welded  portion  has  been  burned,  it  will  be  ex- 
ceedingly porous.  Make  your  weld  as  quickly  as  pos- 


METAL  WELDING  PRACTICE  177 

sible,  as  holding  the  welding  flame  on  the  metal  too 
long  burns  it  and  makes  a  weak,  porous  weld. 

In  welding  brass  use  brass  wire  spelter  which  flows 
more  freely  than  cast  rods.  For  copper  use  a  pure 
copper  rod,  or  if  this  is  not  to  be  had,  soft  copper 
wire  will  do  very  well  for  a  substitute. 

In  welding  bronze  where  the  surface  is  to  be  pol- 
ished and  it  is  necessary  to  keep  the  same  color,  use 
rods  of  the  same  material. 


CHAPTER  XII 

OXY-ACETYLENE    CUTTING 

Oxy- Acetylene  Cutting  Apparatus. — The  process 
of  rapidly  cutting  iron  and  steel  with  the  blowpipe 
and  a  jet  of  oxygen  has  been  considerably  developed, 
especially  in  workshops  using  autogenous  welding, 
since  the  necessary  material,  save  the  blowpipe,  is  the 
same  in  the  two  cases.  The  addition  of  one  or  more 
cutting  blowpipes  to  the  welding  installation  is,  in 
^many  cases,  of  great  value. 

Cutting  blowpipes  consist  of  an  arrangement  for 
giving  a  heating  flame,  generally  that  which  is 
adopted  in  welding  blowpipes,  and  to  which  is  joined 
in  a  permanent  manner  a  second  arrangement  for 
bringing  the  cutting  oxygen,  its  regulation  and  its 
projection  on  the  metal.  The  chief  characteristics  of 
a  good  cutting  blowpipe  are  that  these  arrange- 
ments should  be  so  combined  that  it  is  hardly  pos- 
sible for  them  to  get  out  of  order,  and  of  easy  man- 
agement. 

However,  the  construction  and  regulation  of  cut- 
ting blowpipes  are  not  so  simple  as  this  definition 
might  lead  one  to  believe.  The  form  and  arrangement 
of  the  various  details  have  considerable  influence  not 
only  on  the  good  working  of  the  blowpipe  during  the 
operation,  but  also  on  the  cleanness  of  the  cut  and, 
above  all,  on  the  consumption  of  oxygen. 

In  construction  work  the  line  of  cut  should  bo  as 
clean  as  possible.  The  use  of  a  machine  ho1^-  the 
blowpipe  absolutely  rigid,  always  at  the  same  dis- 
tance, and  allowing  a  very  regular  advancement  ac- 

178 


OXY-ACETYLENE  CUTTING  179 

cording  to  the  cutting,  is  indispensable,  especially  for 
great  thicknesses. 

Portable  Cutting  Apparatus. — Manufacturers  of 
oxy-acetylene  welding  equipments,  especially  of  the 
portable  and  semi-portable  type,  as  a  rule  so  design 
their  apparatus,  that  by  a  few  simple  changes,  it  may 
be  converted  from  a  welding  to  a  cutting  device  in 
a  few  minutes. 

Cutting,  with  this  apparatus,  offers  practically  as 
large  a  field  as  does  welding.  The  saving  in  time 
is  a  great  advantage,  and  besides,  it  is  possible  to 
cut  with  the  oxy-acetylene  blaze  where  it  would  be 
impossible  to  work  with  the  steel  saw  or  cold  chisel. 

The  process  is  used  to  a  large  extent  by  railroads 
for  clearing  up  wrecks  and  for  construction  work  on 
steel  coaches.  It  has  practically  revolutionized  the 
methods  of  constructing  and  wrecking. 

The  metal  to  be  cut  is  heated  with  a  torch  until 
almost  white  hot.  Then  the  extra  cutting  jet  of  pure 
oxygen  is  introduced,  which,  upon  striking  the  heated 
metal  separates  it  with  a  smooth  narrow  cut.  The 
surrounding  metal  is  uninjured.  It  is  not  necessary 
to  go  through  any  preparation  for  this  work,  and 
cutting  can  be  done  in  any  place  that  the  operator 
can  reach  with  the  torch  and  hose  lines.  Metal  of 
practically  any  thickness  can  be  cut  and  any  de- 
sired form  can  be  followed. 

Multiple  Jet  Cutting  Torch. — The  head  or  tip  of 
this  torch  is  so  constructed  that  it  has  six  separate 
and  distinct  heating  jets  or  flames,  evenly  divided 
and  of  exactly  the  same  degrees  of  heat  and  propor- 
tion, arranged  in  a  circle.  The  jets  or  flames  are  all 
controlled  by  a  needle  valve  for  acetylene  and  an- 
other needle  valve  for  oxygen.  The  extra  cutting 


180  OXY-ACETYLENE  WELDING  AND  CUTTING 

jet  for  the  oxygen  supply  is  arranged  in  the  center 
of  these  six  heating  jets,  thus  allowing  the  cutting 
flame  to  act  in  the  hottest  spot  at  all  times.  It  is 
equipped  with  a  two  wheel  carriage  which  can  be 
adjusted  so  that  the  heating  flame  is  at  all  times  the 
proper  distance  from  the  work. 

Lighting  and  Operation. — First  turn  on  the  acety- 
lene and  light  it,  then  turn  on  enough  more  acety- 
lene until  you  have  a  good  strong  flame.  Next  turn 
on  oxygen  slightly — you  will  now  have  a  long  light 
flame.  Keep  turning  on  oxygen  slowly  until  the  long 
white  flame  is  drawn  to  six  small  flames  about  one- 
quarter  inch  long.  Next  turn  on  the  acteylene  until 
the  flame  lengthens  out  to  a  long  white  flame  again, 
then  turn  on  the  oxygen  again  slowly  until  you  get 
the  six  small  white  flames  again.  Continue  to  do  this 
until  you  get  full  heating  capacity.  Next  hold  the 
flame  on  the  work  where  you  are  to  begin  cutting ;  as 
soon  as  the  metal  gets  red,  pull  back  the  lever  on  the 
handle.  This  allows  the  catch  to  fall  into  the  slot 
prepared  for  it,  and  the  cutting  begins  immediately. 

It  is  well  while  cutting  to  dip  the  head  of  the  torch 
in  water  frequently  until  it  gets  quite  cold,  for  the 
reason  that  if  the  head  and  tip  of  the  torch  get  quite 
hot  the  gases  are  expanded  to  an  explosive  point, 
when  it  explodes  in  the  chamber  around  the  inside 
tip,  concentrating  the  flame  direct  on  the  inner  tip 
and  melting  it.  This  can  be  obviated  by  turning  off 
the  gases  frequently  and  cooling  off  the  head  and 
tip  in  water  as  explained. 

Befort  starting  attach  the  fixture  with  the  two 
wheels  at  the  end  of  the  tip,  tighten  it  with  the  screw 
in  the  center.  This  should  be  so  adjusted  that  the 
points  of  the  six  small  white  flames  will  just  touch 


OXY-ACETYLENE  CUTTING  181 

the  work  to  be  cut.  The  tremendous  volume  of  heat 
from  the  cutting  torch  will  melt  any  metal,  so  keep 
the  head  of  the  torch  out  of  holes  or  pockets  if  pos- 
sible ;  if  not,  dip  frequently  in  water  as  explained  in 
foregoing. 

A  combination  welding  and  cutting  equipment  is 
made  which  can  be  instantly  converted  from  a  weld- 
ing to  a  cutting  apparatus,  by  simply  removing  the 
welding  nozzle  and  inserting  the  cutting  nozzle  in 
its  place.  Following  are  the  instructions  for  lighting 
and  operating  this  cutting  torch.  These  instructions 
apply  particularly  to  the  cutting  of  steel. 

Remove  the  welding  tip  and  screw  in  the  cutting 
tip ;  turn  on  sufficient  acetylene  to  blow  away  from 
the  end  of  the  tip,  the  same  as  in  lighting  a  welding 
torch,  then  turn  on  enough  oxygen  to  overcome  the 
acetylene  and  draw  down  to  a  clear  white  cone.  Hold 
the  end  of  the  tip  about  one-half  inch  away  from  the 
metal  to  be  cut  and  move  the  torch  forward  as  fast 
as  you  can  do  so  steadily  and  without  jerking,  as  by 
jerking  it  forward  the  jet  of  oxygen  will  strike  cold 
metal  and  stop  cutting.  Three-eighths  to  one-half 
inch  plate  should  be  cut  at  the  rate  of  one  foot  per 
minute.  Insufficient  pressure  on  either  gas  or  oxygen 
or  striking  the  end  of  the  tip  against  the  metal  will 
cause  the  flame  to  burn  back  in  the  tip.  If  the  flame 
burns  back  in  the  tip  shut  off.  the  gas  at  once  to  pre- 
vent burning  out  the  "thin  central  oxygen  tube. 
When  this  tube  is  spoiled,  unscrew  the  check  in  the 
back  end  of  the  tip,  draw  out  the  old  tube  and  re- 
place it  with  a  new  one,  making  sure  that  the  tube 
is  tight  at  both  ends.  If  the  holes  become  clogged 
with  particles  of  steel,  clean  them  out  with  a  small 
reamer  or  drill,  but  do  not  enlarge  them. 


182  OXY- ACETYLENE  WELDING  AND  CUTTING 

Operating  Cutters. — After  connecting  the  apparatus 
and  seeing  that  everything  is  absolutely  tight,  close 
both  valves  on  the  cutting  torch  and  turn  on  about 
20  Ibs.  pressure  of  oxygen,  still  leaving  the  oxygen 
valve  on  the  cutting  torch  closed. 

Then  turn  on  the  acetylene  and  light  at  the  tip. 
Turn  on  until  the  flame  leaves  the  tip  slightly.  Then 
turn  on  the  oxygen  at  the  handle  of  the  torch,  not  all 
the  way  on,  but  just  enough  to  produce  a  neutral 
ilame  as  for  welding.  Hold  the  torch  at  the  edge  of 
the  metal  to  be  cut,  using  wheel  carriage  to  guide 
the  torch  if  there  is  one,  otherwise  holding  the  nozzle 
about  one-half  inch  from  the  work.  As  soon  as  the 
metal  gets  hot  enough  to  melt,  or  nearly  so,  open  the 
cutting  jet  full  and  proceed  in  the  direction  you 
wish  to  cut. 


CHAPTER  XIII 

OXYGEN  PROCESS  FOR   REMOVAL   OF   CARBON 

Until  recently  the  methods  used  for  removing  car- 
bon deposits  from  gas  engine  cylinders  were  very  im- 
practical and  unsatisfactory.  The  job  meant  dis- 
mantling the  motor,  tearing  out  all  parts,  and  scraping 
the  pistons  and  cylinder  walls  by  hand. 

The  work  was  never  done  thoroughly.  It  required 
hours  of  time  to  do  it,  and  then  there  was  always  the 
danger  of  injuring  the  inside  of  the  cylinders. 

.These  methods  have  been  to  a  large  extent  super- 
seded by  the  use  of  oxygen  under  pressure.  The 
various  devices  that  are  being  manufactured  are 
known  as  carbon  removers,  decarbonizers,  etc.,  and 
large  numbers  of  them  are  in  use  in  the  automobile 
and  gasoline  traction  motor  industry. 

Outfit. — The  oxygen  carbon  cleaner  consists  of  a 
high  pressure  oxygen  cylinder  with  automatic  reduc- 
ing valve,  usually  constructed  on  the  diaphragm  prin- 
ciple, thus  assuring  positive  regulation  of  pressure. 
This  valve  is  fitted  with  a  pressure  gauge,  rubber  hose, 
decarbonizing  torch  with  shut  off  and  flexible  tube  for 
insertion  into  the  chamber  from  which  the  carbon  is  to 
be  removed. 

There  should  also  be  an  asbestos  swab  for  swabbing 
out  the  inside  of  the  cylinder  or  other  chamber  with 
kerosene  previous  to  starting  the  operation.  The 
action  consists  in  simply  burning  the  carbon  to  a  fine 
dust  in  the  presence  of  the  stream  of  oxygen,  this  dust 
being  then  blown  out. 

183 


184  OXY-ACETYLENE  WELDING  AND  CUTTING 

Operation. — The  following  are  instructions  for  oper- 
ating the  cleaner : — 

(1)  Close  valve  in  gasoline  supply  line  and  start 
the  motor,   letting  it  run   until  the   gasoline  is   ex- 
hausted. 

(2)  If  the  cylinders  be  T  or  L  head,  remove  either 
the  inlet  or  the  exhaust  valve  cap,  or  a  spark  plug  if 
the  cap  is  tight.    If  the  cylinders  have  overhead  valves, 
remove  a  spark  plug.     If  any  spark  plug  is  then  re- 
maining in  the  cylinder  it  should  be  removed  and  an 
old  one  or  an  iron  pipe  plug  substituted. 

(3)  Eaise  the  piston  of  the  cylinder  first  to  be 
cleaned  to  the  top  of  the  compression  stroke  and  con- 
tinue this  from  cylinder  to  cylinder  as  the  work  pro- 
gresses. 

(4)  In  motors  where  carbon  has  been  burned  hard, 
the  cylinder  interior  should  then  be  swabbed  with 
kerosene  before  proceeding.    Work  the  swab,  saturated 
with  kerosene,  around  the  inside  of  the  cylinder  until 
all  the  carbon  has  been  moistened  with  the  oil.     This 
same  swab  may  be  used  to  ignite  the  gas  in  the  cyl- 
inder in  place  of  using  a  match  or  taper. 

(5)  Make  all  connections  to  the  oxygen  cylinder. 

(6)  Insert  the  torch  nozzle  in  the  cylinder,  open  the 
torch  valve  gradually  and  regulate  to  about  two  Ibs. 
pressure.     Manipulate  the  nozzle  inside  the  cylinder 
and  light  a  match  or  other  flame  at  the  opening  so 
that  the  carbon  starts  to  burn.     Cover  the  various 
points  within  the    cylinder    and   when    there   is   no 
further  burning  the  carbon  has  been  removed.     The 
regulating  and  oxygen  tank  valves  are  operated  in 
exactly  the  same  way  as  for  welding  as  previously 
explained. 

It  should  be  carefully  noted  that  when  the  piston  is 


OXYGEN  PROCESS  FOR  REMOVAL,  OF  CARBON        185 

up,  ready  to  start  the  operation,  both  valves  must  be 
closed.  There  will  be  a  considerable  display  of  sparks 
while  this  operation  is  taking  place,  but  they  will  not 
set  fire  to  the  grease  and  oil.  Care  should  be  used  to 
see  that  no  gasoline  is  about. 


INDEX 


PAGE 

Accessories    143 

Acetylene    48 

"after  generation"  of 55 

apparatus,  classification  of 56 

composition  of    48 

dissolved  in  acetone 79 

impurity   of    55 

light    78 

piping   109 

plant  installation  <ind  maintenance 75 

plant,  location  of   75 

plant  regulations 76 

polymerization  of  54 

production    of    53 

purification  of   67 

regulation 153 

Acetylene  generators   53,  58 

automatic   56,  63 

capacity  of 64 

carbide  to  water  59 

dipping 58 

granulated  carbide  to  water  60 

non-automatic   56,  63 

requirements    64 

special,   for  welding   65 

wate,r  to  carbide  57 

Adaptability  of  blowpipe  welding 15 

Aluminum  welding 170 

Analysis  of  carbide   52 

of  oxygen    44 

Autogenous   welds    14 

Blowpipe    85 

choice  of   101 

classification    •,  •  •  •   87 

cleaning    106 

for  high  pressure   87,  88 

injector  action 91 

for  low  pressure 87,  90,  102 

for  medium  pressure 87,  90,  102 

maintenance   of    105 

management    104,   148 

186 


INDEX  187 

Blowpipe 

oxy-acetylene    85 

oxy-benz    26 

oxy-coal    gas    25 

oxy-hydrogen 21 

regulation    21 

requirements    86 

weight  of    103 

Blowpipe  welding   14,  96 

various   systems   of    15 

Boyle's  law 37 

Brass  welding  175 

Brazing    12 

Brazing  metals    13 

Bronze    welding    175 

Carbide,  analysis  of 52 

in   compressed   cakes    64 

Carbide  of  calcium    50 

manufacture    of    51 

properties  of   50 

Carbon,  removal  of   183 

Cast  iron  welding   167 

Catalysol    70 

Charging  generators    76 

Cleaning   generators , 76 

Cleaning    welds 162 

Consumption  of  oxygen  and  acetylene   101 

Copper  welding 175 

Cost  of  material 16 

Crankcase    welding 174 

Cutting  apparatus,   oxy-acetylene    178 

Cutting  torch,  multiple  jet 179 

Cutting    operation    180 

Cutting,    oxy-acetylene 178 

Cutting   torch    179 

Cylinders,   handling   of    39 

of  dissolved  acetylene 80 

for    oxygen    34 

Cylinder    valves 40 

Cylinder  welding 168 

Decarbonization    183 

Dissolved  acetylene   79 

advantages  of 83 

Economy    16 

Engine  or  pump  cylinder  welding   168 

Electrolysis  of  water    30 


188  INDEX 

Expansion  and   contraction  precautions    133 

Fire  insurance  regulations   76 

Fire  welding,  advantages  of 10 

Flame,  regulating  the 146 

Flux        10 

Fluxes 163 

Fluxes  for  cast  iron,  steel,  wrought  iron,  copper,  brass, 

bronze  and  aluminum 164 

Forge    welding 10 

Generators,    acetylene 53 

automatic     56,    63 

non-automatic   56,63 

special 65 

Goggles  for  welders  142 

Heat,  utilization  of 21 

HSratol 70 

Hydraulic  valve 114 

Impurities  in  carbide  and  acetylene    67 

Iron  and  steel,  to  restore 141 

Light,   acetylene    78 

Low  pressure,  variable   delivery    P3 

Malleable  iron  welding 1 69 

Operating  cutters 182 

Operating  a  welding  installation 144 

Oxy-acetylene    blowpipe 85 

cutting    178 

Oxy-acetylene  flame  18 

combustion  of  20 

temperature    of    9,  20 

Oxy-benz  blowpipe 26 

Oxy-benz  flame    14,  25 

Oxy-coal  gas   flame 14,25 

Oxy-hydrogen  blowpipe 21 

Oxy-hydrogen  flame 14,   21 

temperature  of   23 

Oxy-hydrogen   for  welding    23 

Oxygen    28 

analysis    of    44 

chemical  properties  of 29 

commercial   guarantee   of 44 

compression  of,  into  cylinders    36 

cylinders    34 

cylinders,  handling  of    39 

from  chlorate  of  potash 34 

from  oxygenite   ' . . .  32 

manufacture    of    .29 


INDEX  189 

Oxygen 

physical  properties  of 28 

pressures   and   temperatures    38 

produced  by  electrolysis  of  water 30 

produced  from  the  air 30 

properties   of 28 

purity    of    43 

reducing  valve   119 

regulation     153 

removal  of  carbon 183 

volume  of,   in   cylinders    36 

Piping,   acetylene 109 

Portable  cutting  apparatus   179 

Portable  welding  outfit 122 

Preparation  of  welds 130 

Precautions    77 

Preheating  and  annealing 133 

Purity  of  oxygen 43 

Purification  of  acetylene   67 

Purifier  position  and   maintenance 74 

Purification,  process  of 69 

Purifiers 72 

Purifying    materials 69 

Quality  of  work 16 

Reducing  valves   40 

Regulating  the  flame   146 

Removal  of  carbon  by  oxygen   . . . . 183 

Restoring  iron  and   steel    141 

Safety 16 

Safety    valves    112 

Steel   welding    165 

Stopping  the  installation 158 

Table,  welding,  how  to  make 127 

Temperature  of  oxy-acetylene  flame   9 

Testing  hydraulic  valve 145 

Thermit   welding    12 

Thick  pieces,  handling 161 

Thin  pieces,   handling    162 

Torch,    see   Blowpipe 

{Torch  lighter   143 

Tubes  and  connectors,  flexible 124 

Valve,  hydraulic   114 

reducing   40,  119 

testing  hydraulic   145 

Valves,  cylinder 40 

leaking   42 

safety    112 


190  INDEX 

Water  gas  welding   11 

Water  to  carbide  generator 57 

Welding    9 

Welding,  blowpipe    14,   96 

Welding  by  water  gas    11 

Welding   flames    18 

compared   26 

Welding  installations   109 

Welding  by   oxy-coal   gas    24 

Welding  practice 163 

Welds,  preparation  of 130 

Welding   procedure    157 

Welding   rod    164 

position   of 152 

Welding   table    12< 

Welding,    thermit    12 

Welding  torches,  characteristics  of 98 

Welding,  various  methods  of  ,,,,,,, 9 


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NOV22  1916 


DEC   6   1916 


4ft  5 


'••x 


1930 

OCT  15  1931 

NOV  2  5  193 


50m-7,'16 


YA  01495 


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